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Note: The AISC Seismic Provisions for Structural Steel Buildings, April 15, 1997, including supplement No. Than that specified in AISC I-9.3b. Doubler plates shall be welded to the column flanges using either a. AISC I-9.7b.
Transcript
Seismic Provisions
for Structural Steel
Buildings
May 21, 2002
for Structural Steel
Buildings
May 21, 2002
Supersedes the Seismic Provisions for Structural Steel Buildings
dated April 15, 1997 including Supplements No. 1 and 2
and all previous versions
dated April 15, 1997 including Supplements No. 1 and 2
and all previous versions
Approved by the AISC Committee on Specifications
and issued by the AISC Board of Directors
and issued by the AISC Board of Directors
AMERICAN INSTITUTE OF STEEL CONSTRUCTION, INC.
One East Wacker Drive, Suite 3100, Chicago, Illinois 60601-2001
One East Wacker Drive, Suite 3100, Chicago, Illinois 60601-2001
ii
Copyright © 2002
by American Institute of Steel Construction, Inc.
All rights reserved. This book or any part thereof must not be reproduced in any form
without the written permission of the publisher.
without the written permission of the publisher.
The AISC logo is a registered trademark of AISC and is used under license.
The information presented in this publication has been prepared in accordance
with recognized engineering principles and is for general information only.
While it is believed to be accurate, this information should not be used or relied
upon for any specific application without competent professional examination
and verification of its accuracy, suitability, and applicability by a licensed
engineer, architect or other professional. The publication of the material
contained herein is not intended as a representation or warranty on the part of the
American Institute of Steel Construction, Inc. or of any other person named
herein, that this information is suitable for any general or particular use or of
freedom from infringement of any patent or patents. Anyone making use of this
information assumes all liability arising from such use.
with recognized engineering principles and is for general information only.
While it is believed to be accurate, this information should not be used or relied
upon for any specific application without competent professional examination
and verification of its accuracy, suitability, and applicability by a licensed
engineer, architect or other professional. The publication of the material
contained herein is not intended as a representation or warranty on the part of the
American Institute of Steel Construction, Inc. or of any other person named
herein, that this information is suitable for any general or particular use or of
freedom from infringement of any patent or patents. Anyone making use of this
information assumes all liability arising from such use.
Caution must be exercised when relying upon other specifications and codes
developed by other bodies and incorporated by reference herein since such
material may be modified or amended from time to time subsequent to the
printing of this edition. The American Institute of Steel Construction, Inc. bears
no responsibility for such material other than to refer to it and incorporate it by
reference at the time of the initial publication of this edition.
developed by other bodies and incorporated by reference herein since such
material may be modified or amended from time to time subsequent to the
printing of this edition. The American Institute of Steel Construction, Inc. bears
no responsibility for such material other than to refer to it and incorporate it by
reference at the time of the initial publication of this edition.
2002 Seismic Provisions
AMERICAN INSTITUTE OF STEEL CONSTRUCTION
AMERICAN INSTITUTE OF STEEL CONSTRUCTION
iii
DEDICATION
Professor Egor Popov
This edition of the AISC Seismic Provisions is dedicated to the memory of Professor
Egor Popov. Professor Popov was a Professor for over 50 years at the University of
California at Berkeley, and a long time member of the AISC Committee on
Specifications. Professor Popov focused a major portion of his career improving the
understanding and seismic performance of steel structures. He was instrumental in
the development of seismic design provisions for steel structures for over thirty
years, and initiated the activity of AISC in this regard in the late 1980’s. As Chair of
TC113 (the predecessor of TC9), he led the publication of the first two editions of
the AISC Seismic Provisions. Until the time of his death at the age of 88 early in
2001, Professor Popov remained a very active member of TC9 in the role of Vice
Chair. His contributions to the development of these provisions and the
understanding of the seismic performance of steel buildings is unequaled, and will
long be remembered and appreciated by AISC, the steel industry and the structural
engineering profession. It is entirely fitting that these provisions be dedicated to the
memory of Professor Egor Popov.
Egor Popov. Professor Popov was a Professor for over 50 years at the University of
California at Berkeley, and a long time member of the AISC Committee on
Specifications. Professor Popov focused a major portion of his career improving the
understanding and seismic performance of steel structures. He was instrumental in
the development of seismic design provisions for steel structures for over thirty
years, and initiated the activity of AISC in this regard in the late 1980’s. As Chair of
TC113 (the predecessor of TC9), he led the publication of the first two editions of
the AISC Seismic Provisions. Until the time of his death at the age of 88 early in
2001, Professor Popov remained a very active member of TC9 in the role of Vice
Chair. His contributions to the development of these provisions and the
understanding of the seismic performance of steel buildings is unequaled, and will
long be remembered and appreciated by AISC, the steel industry and the structural
engineering profession. It is entirely fitting that these provisions be dedicated to the
memory of Professor Egor Popov.
2002 Seismic Provisions
AMERICAN INSTITUTE OF STEEL CONSTRUCTION
AMERICAN INSTITUTE OF STEEL CONSTRUCTION
iv 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .
1999) and No. Part III is an allowable stress design alternative to the LRFD provisions for structural steel buildings in Part I. and other sources. Supplement No. Accordingly. The first letter(s) of words or terms that appear in the glossary are generally capitalized throughout these Provisions. 1997. but is included for information purposes only. These provisions were also modified to be consistent with the 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . Supplement Number 2 to the 1997 AISC Seismic Provisions was published on November 10. The previous edition of the AISC Seismic Provisions for Structural Steel Buildings. 2000. incorporated many of the early advances achieved as part of the FEMA/SAC program and other investigations and developments related to the seismic design of steel buildings. 1 (February 15. Part II is intended for the design and construction of composite structural steel/reinforced concrete buildings. 2 (November 10. 2000) to the 1997 Seismic Provisions. a list of Symbols. especially moment frames. 1999. In addition. a Glossary. published on April 15. This commitment was intended to keep the provisions as current as possible. This document. 1 to the 1997 AISC Seismic Provisions. three appendices. and a non-mandatory Commentary with background information are provided. v PREFACE (This Preface is not a part of ANSI/AISC SSPEC-2002. the AISC Seismic Provisions for Structural Steel Buildings (hereafter referred to as Seismic Provisions) is a separate consensus document that addresses one such topic: the design and construction of structural steel and composite structural steel/reinforced concrete building systems for seismic demands. Recognizing that rapid and significant changes in the knowledge base were occurring for the seismic design of steel buildings. The first such supplement was completed and published on February 15. which culminated late in 2000. Seismic Provisions for Structural Steel Buildings. These Provisions are presented in three parts: Part I is intended for the design and construction of structural steel buildings. Additional revisions resulted from considering new information generated by the FEMA/SAC project. it is not feasible for it to also cover the many special and unique problems encountered within the full range of structural design practice. using LRFD. the AISC Specifications Committee committed to generating frequent supplements to the Seismic Provisions.) The AISC Load and Resistance Factor Design (LRFD) Specification for Structural Steel Buildings is intended to cover the common design criteria in routine office practice. This edition of the AISC Seismic Provisions incorporates Supplements No.
units) are based on IEEE/ASTM SI 10.9. The equations are non-dimensionalized where possible by factoring out material constants.4 and 9. A major update to the commentary to these provisions is also provided. Specific changes to these provisions include the following: • A clarification to the glossary to verify that chord and collector/drag elements in floor diaphragms are considered to be part of the seismic force resisting system. • Increasing the moment frame column splice requirements to reflect the FEMA/SAC recommendations. such as E.S. • Incorporating FEMA/SAC recommendations for weld access holes in OMF systems. • Additional requirements for the toughness of filler metals to be used in complete joint penetration welds in intermediate and special moment frame systems. • Dual units format. • A revision to clarify member slenderness ratio requirements and better coordinate with the LRFD provisions. This allows these provisions to be incorporated by reference into both the 2003 IBC and 2002 NFPA 5000 building codes that use ASCE 7-02 as their basis for design loadings.S. • Increasing SMF web connection design requirements to be consistent with the FEMA/SAC recommendations. Task Committee 9—Seismic Provisions is responsible for the ongoing development of these Provisions. • Incorporating FEMA/SAC recommendations for the removal of weld backing and run-off tabs in OMF systems. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . including the provision of a required stiffness to be consistent with Section 3 of LRFD. • Adding a new appendix (Appendix P) that defines procedures to be used in the pre-qualification of moment connections. The AISC Committee on Specifications. they are being republished in their entirety. Because the scope of changes that have been made to these provisions since 1997 is so large.vi ASCE 7-02 document. • Adding a section on the use of H-pile members. Standard for Use of the International System of Units (SI): The Modern Metric System. This version also includes Errata to Sections 8. The metric conversions (given in parentheses following the U. customary and metric units. • Clarifying column base design demands for various systems. Minimum Design Loads for Buildings and Other Structures. including grinding surfaces to adequate smoothness. • Clarifying lateral bracing requirements of moment frame beams. • Requiring that splices of columns that are not part of the moment frames develop a minimum shear force. Values and equations are given in both U.
the members of AISC Committee on Specifications. Fisher Donald R. and suggestions for improvement. Murray Shu-Jin Fang R. Leon Gregory G. Vice-Chairman Patrick M. Thornton Louis F. Fenves Jack E. R. Task Committee 9 – Seismic Design: James O. Barsom Lawrence A. Pinkham Roger E. By. Holland John M. Ellingwood Thomas M. Miller Bruce R. Gross Roger E. as described more fully in the disclaimer notice preceding the Preface. Lanz. Brockenbrough Richard W. Swensson John L. the National Science Foundation (NSF). Kloiber Willam D. Fraser Thomas A. Yura Cynthia J. Bast Roberto T. Martin Gregory G. The reader is cautioned that professional judgment must be exercised when data or recommendations in these provisions are applied. Ellifritt Duane K. Malley. Fisher Douglas A. Sabol Subhash Goel Kurt D. Vice-Chairman James R. Ferch. Chairman John L. Ferch Rafael Sabelli Timothy P. AISC further acknowledges the significant contributions of several groups to the completion of this document: the Building Seismic Safety Council (BSSC). Chair James R. Secretary 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . Deierlein David L. Lindsey. Secretary Approved by the AISC Committee on Specifications. vii The AISC Committee on Specifications gives final approval of the document through an ANSI accredited balloting process. Engelhardt Clarkson W. Lanz. Petersen James M. and has enhanced these Provisions through careful scrutiny. Geschwindner Raymond H. Harris Hansraj G. McKenzie Duane S. Fraser W. Drake Harry W. Deierlein Robert Lyons Richard M. Baker Mark V. Gross Nabih F. Rees-Evans John W. Martin Michael D. Leon Reidar Bjorhovde James O. Marshall Wai-Fah Chen Harry W. Stanley D. and the Structural Engineers Association of California (SEAOC). Sherman Timothy P. G. Griffis Joseph A. discussion. Shankar Nair Steven J. Lee Shoemaker Theodore V. Ashar Tony Hazel William F. the Federal Emergency Management Agency (FEMA). Galambos William A. Youssef Cynthia J. the SAC Joint Venture. Harris Mark Saunders. Tide Lawrence G. Hassett Roy Becker Roberto T. Malley Roger L.
viii 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .
.. Panel Zone of Beam-to-Column Connections.................................................................................... 1......................................................................................... 3............................................................ 4.................... Column-Beam Moment Ratio....................................................... CONNECTIONS................................................................................................... Beam and Column Limitations .................................................. 2....................................... Material Specifications.............. 4................... 2................................ 8........PROVISIONS SYMBOLS ......................... 2.......................................................................................................... Other Connections................................................................................ Beam and Column Limitations......................................................... 9..................................................................................................... 7...................... GENERAL SEISMIC DESIGN CATEGORIES.............................................................. Beam-to-Column Connection Restraint........................................................................................................................................................... INTERMEDIATE MOMENT FRAMES (IMF) ......................... Scope.............................. Local Buckling............................................. 4.................. AND STANDARDS ....................... MATERIALS ......... JOINTS.................................. 3............................. LOAD COMBINATIONS.................... Bolted Joints ............................................... Scope..................... 1.................... 2................................ Welded Joints ............................................... Continuity Plates............................................................................ Column Splices................................................................ 3............ Lateral Bracing of Beams .............................. Panel Zone of Beam-to-Column Connections .............. LOADS... 7........................................................... 5...................................................................................................................................................................................... MEMBERS................................................................................... ix TABLE OF CONTENTS PART I STRUCTURAL STEEL BUILDINGS ........ Material Properties for Determination of Required Strength............................................................. Scope............................................. GLOSSARY ............................. REFERENCED SPECIFICATIONS. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION ................................................... Notch-toughness Requirements... 10............................................................................ Nominal Strength .................................................. 1......................................... Column Strength .............. STORY DRIFT .......... 1...................................................... Column Bases................................................. SPECIAL MOMENT FRAMES (SMF) ...... Scope ........ 6.......... H-Piles ...................... CODES............................. 2..... 1.............................. Loads and Load Combinations......................................................... Column Splices............................... 8.................................. 4. Beam-to-Column Joints and Connections ............................................ 2... 3....................................... 5.................................................................... 2........................................................................... 5................................... AND FASTENERS ................................................ 6................... 9..................................................................................................................................................................... 4........................ AND NOMINAL STRENGTHS .......... 3............ Beam-to-Column Joints and Connections .. 3....... SCOPE ......................................................... 1..... 1.......................... 6........................
.................. Beam-to-Column Connection Restraint ............................ 1................... QUALITY ASSURANCE ......... 16............... Lateral Bracing.......................................................... 3..................................................... 6................................................................................................................................................ Column-Beam Moment Ratio ............................ 2................................................................................................................................. Column-Beam Moment Ratio............ Special Bracing Configuration Requirements ............................................................................................... 4..................................................... 3............................................................................. Lateral Bracing of Link............................................................. 5....................... Lateral Bracing of Beams...................................................................... 1............................... 5.......................................................................................................................... Column Splices............ 9............................................... 1........................ Special Segment................................................................................. Beam-to-Column Connections........................................... Scope...... ORDINARY MOMENT FRAMES (OMF)........................................ 1.............................. 8............................. Bracing Connections...................................................................................... 8............. 7............x PART I (continued) 5....................................................... Link Stiffeners .............................. 7....................................................... SPECIAL CONCENTRICALLY BRACED FRAMES (SCBF) .................................... Bracing Members......................................................................... 4............................................................................................ 9.......................... 3....................................................................... Scope................................... APPENDIX P............................................. 2....... 15................................................. Nominal Strength of Special Segment Members............ 1.................... Scope................ PREQUALIFICATION OF BEAM-TO-COLUMN AND LINK- TO-COLUMN CONNECTIONS 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION ......................................................................................................................................................................... Compactness ........ 6.................................... Diagonal Brace and Beam Outside of Link .................................................... Beam-to-Column Joints and Connections .................... 5.... Columns ... Column Splices............. 3......... ORDINARY CONCENTRICALLY BRACED FRAMES (OCBF)..................................... 2................................................... Beam and Column Limitations .............. 13........... Nominal Strength of Non-special Segment Members ... 11.................................. Strength .................................... Lateral Bracing of Beams....... Required Column Strength ............... Continuity Plates ................ 7..................................... Scope.. 4. 5....... Link-to-Column Connections ................................................................................. 4........................................ Scope...................... 2......................................................................................................................................... ECCENTRICALLY BRACED FRAMES (EBF) .... 2........................................................................................................................................... 12............................................................................. 6...................................................... SPECIAL TRUSS MOMENT FRAMES (STMF)....................................................................... Continuity Plates........... Links ..................................... Beam-to-Column Connection Restraint.............. 6............................................... Panel-Zone of Beam-to-Column Connections............. 14............................ 8..............................
.......................................................................................................................................................... 5............................................................................................................................................................................ SCOPE..................................................................................... 2............................................................. S2.................... General Requirements .......................................................... QUALIFYING CYCLIC TESTS OF BEAM-TO-COLUMN AND LINK- TO-COLUMN CONNECTIONS ...... Methods of Tension Testing ........... DESIGN PROCEDURE P6..... S6................................................ Material Strength................................................. WELD METAL/WELDING PROCEDURE SPECIFICATION TOUGHNESS VERIFICATION TEST ...................... X1............................................................................................................................ INSTRUMENTATION................................................................................. TESTING REQUIREMENTS P4................................ S4....... ESSENTIAL TEST VARIABLES . Continuity Plates ... 7............................................................................................. SCOPE AND PURPOSE .................. Bolts.......... 3................................................................ SYMBOLS .................................................................................................. DEFINITIONS........... Size of Members............................. X3........ LOADING HISTORY .... ACCEPTANCE CRITERIA ...................... S3............................................................................................. 3............ Basis for Prequalification 2................ 6..................................................................................................................................... TEST SUBASSEMBLAGE REQUIREMENTS ..................................... Authority for Prequalification P3....... PART II COMPOSITE STRUCTURAL STEEL AND REINFORCED CONCRETE BUILDINGS GLOSSARY 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION ............................................................................................................. Loading Sequence for Link-to-Column Connections .................. SCOPE P2................. S5... S9......... ACCEPTANCE CRITERIA ................ S7........................................................................................................................................ 4.................... TEST REPORTING REQUIREMENTS...................................................... TEST SPECIMENS ......... X4........................ S8.................................... MATERIALS TESTING REQUIREMENTS ............................... S10.............. Loading Sequence for Beam-to-Column Moment Connections............. Sources of Inelastic Rotation........... X2....... 2... 1....................................... 2. 1................................................... S1......... APPENDIX X........... 1................ GENERAL REQUIREMENTS 1.. xi PART I (continued) P1... Welds...... TEST CONDITIONS ........................ PREQUALIFICATION VARIABLES P5....................................................................... Tension Testing Requirements .................................... Connection Details ..... PREQUALIFICATION RECORD APPENDIX S........................
.................... 3....... Braces........................ Reinforced-concrete-encased Composite Columns. Moment Connections ..................... 4............................................ 3................................. Beams................... 9............................ 5......................................... PART II (continued) 2................................................... 1.............................. 1.............................................................................................................................................................................. Connections.......................................... 5.................................................................................................................... AND NOMINAL STRENGTHS.............................................. 1................................................................. Partially Restrained (PR) Moment Connections .... COMPOSITE ORDINARY BRACED FRAMES (C-OBF)............................................................................. 5........ 2............... 2.......... LOAD COMBINATIONS............................................. 3................... 3............. Scope....................................................................................................................................................... LOADS......................... COMPOSITE MEMBERS........................................... Scope ... 1........................................ Composite Beams................................................ 7............................................ 3........................................................................ 4.... Composite Beams......................................................................................................... Moment Connections ............................... 4........................................ 6............ 2......... Scope ......... 10........ 2............................... 5.............................. Scope .............. COMPOSITE ORDINARY MOMENT FRAMES (C-OMF) 1............ 4........................ COMPOSITE CONNECTIONS................................................................................................................ 1.................................................................................................................. 4................................................... 2............. 8.................................. General Requirements ................................ SEISMIC DESIGN CATEGORIES ............................................................................... 13...................................... SCOPE .............................. Beams ............................................. Composite Floor and Roof Slabs......................................Concrete-filled Composite Columns ................................................... 3................ Structural Steel ............... 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .......... AND STANDARDS......... MATERIALS............................................................................. Columns .......... COMPOSITE PARTIALLY RESTRAINED (PR) MOMENT FRAMES (C-PRMF) 1................................................... 5................. REFERENCED SPECIFICATIONS......................................................................... 12.............................. COMPOSITE SPECIAL MOMENT FRAMES (C-SMF) ............................................................................. COMPOSITE INTERMEDIATE MOMENT FRAMES (C-IMF) ...................................... Nominal Strength of Connections .............................................................................................................................................. CODES................................................................................... 2.................. Moment Connections ............................................... Column-Beam Moment Ratio .................................................................................. COMPOSITE CONCENTRICALLY BRACED FRAMES (C-CBF) ..................................................... Columns.... 4......................... 3................. Scope .................... Columns .................................... Beams............... 3.... Scope ............................................................................................................................................................ 11........................................... 2............................................................. 2.................................................................. Concrete and Steel Reinforcement ................. Beams................................xii 1..................... Columns.............. Columns ................................................. Scope ............................................ 1....................
............................................................................................................ CODES.......................................................................... 2......................... ORDINARY CONCENTRICALLY BRACED FRAMES (OCBF) ............................................................................................ 2........................................ 12...... 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION ............................................................................ Coupling Beams ... Bracing Connections......... LOADS............................................................................... SCOPE........................................... Boundary Members..... 3............. Beam-to-column Connection Restraint ....... Strength ........................................ LOAD COMBINATIONS........... JOINTS................................................................................. 6.................................... Columns..................................... SPECIAL TRUSS MOMENT FRAMES ............................................................................. 3............................................................... 2.. SPECIAL REINFORCED CONCRETE SHEAR WALLS COMPOSITE WITH STRUCTURAL STEEL ELEMENTS (C-SRCW).................................... 2................................. Nominal Strength .. 2.................................. Scope............... 1...................................................... REFERENCED SPECIFICATIONS..................................... SPECIAL MOMENT FRAMES ........................................................................... 5............................................................. Braces.................................................................................. PART III ALLOWABLE STRESS DESIGN (ASD) ALTERNATIVE 1.............. ORDINARY REINFORCED CONCRETE SHEAR WALLS COMPOSITE WITH STRUCTURAL STEEL ELEMENTS (C-ORCW) 1................................. 2............. 3............................................ Columns .................... 3................. PART II (continued) 2....................................... 2............................................................................................... Design Strength .................................................................... 14.......................................... Connections...... 4.......................... Links .............. 4.......... Boundary Members.............................................................................................................. 3.... 7......... 4..... COMPOSITE ECCENTRICALLY BRACED FRAMES (C-EBF) ....... 14............................ 9........................ Scope........................................................ Beams ... CONNECTIONS............................... 15................................................... 17...................................................................... 4..................... Boundary Members............................................. 1........................................................ Panel Zone of Beam-to-column Connections ........ SPECIAL CONCENTRICALLY BRACED FRAMES (SCBF)............................................................................................... AND STANDARDS..................................................................................... Lateral Bracing ......................................................... 3... 3.................................................... 13................................................................................................. 7............................... Wall Element ................... 2................................................................ Nominal Strength of Non-special Segment Members........ Scope........................... COMPOSITE STEEL PLATE SHEAR WALLS (C-SPW) ....................... AND FASTENERS....................................................... Scope .......................... AND NOMINAL STRENGTHS...................... Coupling Beams................ 1...................... Braces................. 5. xiii 1.......... Bolted Joints ................. Scope................................................................ 16..............................................................................................................
............................................................................................................................... Continuity Plates................................................................................................................. SPECIAL CONCENTRICALLY BRACED FRAMES (SCBF).......................................................................................................................... 1............. AND FASTENERS ....... 1...................................... Welded Joints..... Column Splices ....... Column-Beam Moment Ratio....... Column Bases ...................... 4............................... Scope............................................... Beam and Column Limitations ........... 2............................... Lateral Bracing of Beams ................................... 4................................. 7.................................. Beam-to-Column Joints and Connections..... 6..... JOINTS... Compactness ....... 3................ STORY DRIFT ....................... 2........ INTERMEDIATE MOMENT FRAMES (IMF) ............................................. 4................................................ 4.............................................. MEMBERS.................. 2............... Bolted Joints .. Scope ................................................ 1....................... H-Piles.................... SPECIAL TRUSS MOMENT FRAMES (STMF) ......... C4.................................. 1................................... SPECIAL MOMENT FRAMES (SMF) ............ Continuity Plates ............................................................... 3..................................................................................................................... C13.................... 6................ Beam-to-Column Joints and Connections ....................... LOADS... C6....................... C10.................................................................................................................................................... Beam-to-Column Joints and Connections . C3...................................................................................................................................................... 2....xiv COMMENTARY PART I STRUCTURAL STEEL BUILDINGS C1. 3............ Scope.................................................................................................................... Material Specifications............. 8................................. Column Strength ................................. 5..... C7........... 2................................................ Notch-toughness Requirements.. 5.... Material Properties for Determination of Required Strength ............................ C8........................... CODES.................................... ORDINARY MOMENT FRAMES (OMF) ........................................................................................ C9............................................................................................. 5........................... Scope.................................. 6................... C2. LOAD COMBINATIONS.............................................. CONNECTIONS......... AND STANDARDS ....................... C5................................. Scope 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .... MATERIALS ................. 1................................................................................................ C12................. Special Segment.......................... Beam-to-Column Connection Restraint........................ Panel Zone of Beam-to-Column Connections ....................................................... Other Connections................................................. 3..... Nominal Strength of Special Segment Members................................................... 5.......... 2. Lateral Bracing................................................................................................................................................................... C11...................................................... SCOPE ............................... GENERAL SEISMIC DESIGN CATEGORIES................... REFERENCED SPECIFICATIONS............................................. Nominal Strength of Non-special Segment Members ......................................................... 3................................................................ AND NOMINAL STRENGTHS ...................................................... 1..................................................
.................................. Strength .................................................................... Columns .................................................. CS5................................................... SEISMIC DESIGN CATEGORIES ................................................. 2.............................. 5................................. LOADING HISTORY ...................................................................... Composite Floor and Roof Slabs. 5................................. LOAD COMBINATIONS............... APPENDIX S............................................ QUALIFYING CYCLIC TESTS OF BEAM-TO-COLUMN AND LINK-TO-COLUMN CONNECTIONS .. Lateral Bracing of Link.......................... SCOPE ..................................................... AND NOMINAL STRENGTHS C5......................................................................... Sources of Inelastic Rotation .............. C4. 4...................................... Beam-to-Column Connection .............................................................................................................. Reinforced-concrete-encased Composite Columns........................................ 5........ ECCENTRICALLY BRACED FRAMES (EBF) ................................ TEST SUBASSEMBLAGE REQUIREMENTS ........... CODES.......................................... MATERIALS TESTING REQUIREMENTS........................................................................................................................................................................ Scope.. ORDINARY CONCENTRICALLY BRACED FRAMES (OCBF) ............................. REFERENCED SPECIFICATIONS.................................................... Bracing Connections........................................................................ CS10................................... CS1...... 1............ C14............... 7... C15.................................. C2........... Required Column Strength ....................................................... CS8........................................................................................... C3............... DEFINITIONS......... Concrete-filled Composite Columns ........................... 6............................................................................................................ 5............... C16.............................. AND STANDARDS ..... Diagonal Brace and Beam Outside of Links.................................... 4.................................... 3..................................................................................... C6.......... Welds ............ Link-to-Column Connections .................. 1. ACCEPTANCE CRITERIA........... 3............................................................................................ Link Stiffeners ........................................................... 1..... xv PART I COMMENTARY (continued) 2............................. Bracing Members......................................... MATERIALS................................................................................................................................................................... Scope .......... LOADS...... Special Bracing Configuration Requirements .... 8........ ESSENTIAL TEST VARIABLES .. COMPOSITE MEMBERS ........................................................................................................ PART II COMPOSITE STRUCTURAL STEEL AND REINFORCED CONCRETE BUILDINGS C1................................................ 2.................................................... SCOPE AND PURPOSE ........................ CS4........ QUALITY ASSURANCE ..................................................... 6......... Scope....................... Composite Beams....................................... CS3........................................... 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION ............... 1............................................... 2...... 2................................................................................................. Links .............................. 4.......... 3.................................................................................. Size of Members .................................................................. CS6................................................................................. Material Strength .............
......... C15.................................................. C8.................................................................... 3.. C14................................................................... C10.................. C17......................................... 1..... Scope . 3.xvi PART II COMMENTARY (continued) C7............................................................. LOADS................................................... SCOPE ................... AND NOMINAL STRENGTHS .. C13............................................... C11........... Scope....... ORDINARY REINFORCED CONCRETE SHEAR WALLS COMPOSITE WITH STRUCTURAL STEEL ELEMENTS (C-ORCW) C16.............. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION ............................................................. General Requirements................. COMPOSITE ORDINARY BRACED FRAMES (C-OBF) ............ 1.............................................................................. LIST OF REFERENCES .................................... C4............ LOAD COMBINATIONS................................. COMPOSITE INTERMEDIATE MOMENT FRAMES (C-IMF)............................................. 2.............................. COMPOSITE CONNECTIONS ............ SPECIAL REINFORCED CONCRETE SHEAR WALLS COMPOSITE WITH STRUCTURAL STEEL ELEMENTS (C-SRCW) ........ COMPOSITE PARTIALLY RESTRAINED (PR) MOMENT FRAMES (C-PRMF) C9........................................................... Beams........................................................................... COMPOSITE ECCENTRICALLY BRACED FRAMES (C-EBF)....... Moment Connections ........ COMPOSITE CONCENTRICALLY BRACED FRAMES (C-CBF) .. Nominal Strength of Connections..................... COMPOSITE SPECIAL MOMENT FRAMES (C-SMF).. 4................... COMPOSITE STEEL PLATE SHEAR WALLS (C-SPW) ..... COMPOSITE ORDINARY MOMENT FRAMES (C-OMF) C12.................................................................. PART III ALLOWABLE STRESS DESIGN (ASD) ALTERNATIVE C1................ Nominal Strength ......... 2.........
xvii 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .
kip-in. Af Flange area. kip-in.2 (mm2) (I-15) D Dead load due to the weight of the structural elements and permanent features on the building.2 (mm2) (I-15) Aw Link web area. (N-mm) (I-11) Mnc Nominal flexural strength of the chord member of the special segment.2 (mm2) (II-17) Ast Area of Link stiffener. kips (N) (I-9) Outside diameter of round HSS. in. in. (N-mm) (I-15) Mpc Nominal plastic flexural strength of the column. (mm) (I-12) Lp Limiting laterally unbraced length for full plastic flexural strength.2 (mm2) (II-6) Ash Minimum area of tie reinforcement. in. (N-mm) (I-9) Mu Required flexural strength of a member or joint. ksi (MPa) (I-7) H Height of story. kips (kN) (I-9) Span length of the truss. (N-mm) (I-12) Mp Nominal plastic flexural strength. or the distance between the top of floor slabs at each of the levels above and below. ksi (MPa) (I-9) Fyf Fy of column flange. uniform moment case.2 (mm2) (II-6) Asp Horizontal area of the steel plate in composite shear wall. kip-in. (mm) (Table I-8-1) E Effect of horizontal and vertical earthquake-induced loads (Glossary) Es Modulus of elasticity of steel. ksi (MPa) (I-8) Fyh Specified minimum yield strength of transverse reinforcement. in. (I-6) Fyb Fy of a beam. (N-mm) (I-8) Mv Additional moment due to shear amplification from the location of the plastic hinge to the column centerline. (mm) (I-8) K Effective length factor for prismatic member. kip-in.000 ksi (200 000 MPa) (I-8. ksi (MPa) Fu Specified minimum tensile strength. in. kip-in.2 (mm2) (I-9) As Cross-sectional area of structural steel elements in composite members. in. (I-13) L Live load due to occupancy and moveable equipment.2 (N-mm2) (I-12) Fy Specified minimum yield stress of the type of steel to be used. (N-mm) (I-9) 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . II-6) EsI Flexural elastic stiffness of the chord members of the special segment. ksi (MPa). in. kip-in. (mm) (I-12) Mn Nominal flexural strength. Es = 29. in. which may be taken as the distance between the centerline of floor framing at each of the levels above and below. in. 'yield stress' denotes either the minimum specified yield point (for those steels that have a yield point) or the specified yield strength (for those steels that do not have a yield point). (mm) (I-12) Ls Length of the special segment. in. (N-mm) (I-9) Mpa Nominal plastic flexural strength modified by axial load. As used in the LRFD Specification. ksi (MPa) (II-6) Fyw Fy of the panel-zone steel. kip-in. in.1 Symbols Numbers in parentheses after the definition of a symbol refer to the Section in either Part I or II of these Provisions in which the symbol is first used. ksi (MPa) (I-9) Fyc Fy of a column. in.2 (mm2) (I-8) Ag Gross area. kip-in.
in. (mm) (II-6) Z Plastic section modulus of a member. in. in. (mm) (I-9) dc Overall column depth. kips (N) (II-6) Pu Required axial strength of a column or a Link. in. in. (mm) (II-6) d Nominal fastener diameter. (mm) (II-6) l Unbraced length between stitches of built-up bracing members. kips (N) (I-9) Qb Maximum unbalanced vertical load effect applied to a beam by the braces. kips (N) (I- 12) Po Nominal axial strength of a composite column at zero eccentricity. in.3 (mm3) (I-9) a Angle that diagonal members make with the horizontal (I-12) b Width of compression element as defined in LRFD Specification Section B5. in. kips (N) (I-13) Rn Nominal strength Ru Required strength (I-9) Rv Panel-zone nominal shear strength (I-9) Ry Ratio of the Expected Yield Strength to the minimum specified yield strength Fy (I-6) S Snow load. kips (N) (I-15) Vu Required shear strength of a member. in. kips (N) (I-15) Vns Nominal shear strength of the steel plate in a composite plate shear walls. (mm) (I-9) dz Overall panel-zone depth between continuity plates. (mm) (I-9) s Spacing of transverse reinforcement measured along the longitudinal axis of the 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . in. (mm) (I-9) bw Width of the concrete cross-section minus the width of the structural shape measured perpendicular to the direction of shear. kips (N) (I-8) Nominal axial strength of a composite column. kips (N) (I-12) Pnt Nominal axial tensile strength of diagonal members of the special segment. in. kips (N) (II-9) Puc Required axial strength of a column in compression. kips (N) (I-15) Vpa Nominal shear strength of an active Link modified by the axial load magnitude. in. in. which is equal to FyAg. kips (N) (I-9) Vn Nominal shear strength of a member. (mm) (I-13) r Governing radius of gyration. (mm) (Table I-8-1) bcf Width of column flange. in. kips (N) (I-9) Py Nominal axial yield strength of a member. (mm) (I-15) f’c Specified compressive strength of concrete. in. kips (N) (II-6) Pnc Nominal axial compressive strength of diagonal members of the special segment. (mm) (I-7) db Overall beam depth. in. kips (N) (I-8) Required axial strength of a composite column. ksi (MPa) (II-6) hcc Cross-sectional dimension of the confined core region in composite columns measured center-to-center of the transverse reinforcement. in. (mm) (I-13) Unbraced length of compression or bracing member. (mm) (I-9) bf Flange width. (mm) (I-9) e EBF Link length. kips (N) (I-9) Ycon Distance from top of steel beam to top of concrete slab or encasement. in. (mm) (I-9) ry Radius of gyration about y axis. 2 Pn Nominal axial strength of a column.1.3 (mm3) (I-9) Zc Plastic section modulus of the column. kips (N) (II- 17) Vp Nominal shear strength of an active Link.
(mm) (I-7) Thickness of element. in. in. (mm) (Table I-8-1) wz Width of panel-zone between column flanges. (mm) (I-9) tcf Thickness of column flange. in. (mm) (II-6) t Thickness of connected part. in. reduced by the axial stress Puc/Ag. (mm) (I-9) tw Thickness of web. (mm) (Table I-8-1) Thickness of column web or doubler plate. Maximum developed moments shall be determined from test results (I-9) Ωo Horizontal seismic overstrength factor (I-4) δ Deformation quantity used to control loading of the Test Specimen (S6) δy Value of deformation quantity δ at first significant yield of Test Specimen (S6) ρ' Ratio of required axial force Pu to required shear strength Vu of a Link (I-15) λ Slenderness parameter (I-13) λps Limiting slenderness parameter for compact element (Table I-8-1) φ Resistance factor (I-8) φc Resistance factor for compression (I-13) φv Resistance factor for shear strength of panel-zone of beam-to-column connections (I-9) Resistance factor for the shear strength of a composite column (II-6) γ Link Rotation Angle (S2) 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .3 structural composite member. in. (mm) (I-9) tbf Thickness of beam flange. (mm) (I-9) tf Thickness of flange. from the top and bottom of the beam moment connection (I-9) ΣM*pb Moment at the intersection of the beam and column centerlines determined by projecting the beam maximum developed moments from the column face. in. in. (mm) (I-9) z Minimum plastic section modulus at the Reduced Beam Section. in. in. in. in. (mm) (I-9) tp Thickness of panel-zone including doubler plates.3 (mm3) (I-9) ΣM*pc Moment at beam and column centerline determined by projecting the sum of the nominal column plastic moment strength.
including the effects of inelastic action). SCBF or OCBF). Design story drift. connectors. Column stiffeners at the top and bottom of the panel-zone. In the absence of an Applicable Building Code. (3) each system designed to resist the total lateral load in proportion to its relative rigidity. Braced frame. also known as transverse stiffeners. usually a horizontal member in a seismic frame system. shear. Applicable building code. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . The probable yield strength of the material. where E and the horizontal component of E are defined in the Applicable Building Code. as appropriate) provided by element or connection. multiplied by Ry . Authority having jurisdiction. Connection. Inclined structural members carrying primarily axial load that are employed to enable a structural frame to act as a truss to resist lateral loads. The assemblage of plates. Resistance (force. Eccentrically braced frame (EBF). political subdivision. determined as specified in the Applicable Building Code. equal to the minimum specified yield strength. Expected yield strength. bolts. The building code under which the building is designed. Fully restrained (FR). Dual system. office or individual charged with the responsibility of administering and enforcing the provisions of this standard. IMF or OMF) that are capable of resisting at least 25 percent of the base shear. moment. A structural member that primarily functions to carry loads transverse to its longitudinal axis. Beam. A diagonally braced frame meeting the requirements in Section 15 that has at least one end of each bracing member connected to a beam a short distance from another beam-to-brace connection or a beam-to-column connection. Connections are categorized by the type and amount of force transferred (moment. the loads and load combinations shall be those stipulated in ASCE 7. A vertical truss system of concentric or eccentric type that resists lateral forces on the structural system. A Dual System is a structural system with the following features: (1) an essentially complete space frame that provides support for gravity loads. and concrete or steel shear walls. Sufficient rigidity exists in the connection to maintain the angles between intersecting members. (2) resistance to lateral load provided by moment resisting frames (SMF. and. Amplified seismic load. The earthquake represented by the Design Response Spectrum as specified in the Applicable Building Code. or steel braced frames (EBF. The organization. stress. Design strength. and rods at the base of a column used to transmit forces between the steel superstructure and the foundation. Continuity plates. Column base. PART I 4 Part I—Structural Steel Buildings Glossary The first letter(s) of words or terms that appear in this glossary are generally capitalized throughout these Provisions. A combination of joints used to transmit forces between two or more members. the product of the nominal strength and the resistance factor. end reaction). The horizontal component of earthquake load E multiplied by Ωo. Design earthquake. Diagonal bracing. The amplified story drift (drift under the design earthquake. Fy.
The inelastic angle between the Link and the beam outside of the Link when the total story drift is equal to the Design Story Drift. A building frame system in which seismic shear forces are resisted by shear and flexure in members and connections of the frame. Nominal strength. See V-Braced Frame Joint. Nominal loads. moment. Lateral bracing member. Partially restrained (PR). A method of proportioning structural components (members. Prequalified connections.delta effect. See Figure C-I-6. allowing for modeling effects and differences between laboratory and field conditions. An area of potentially reduced notch-toughness located in the web-to-flange fillet area. A connection with insufficient rigidity to maintain the angles between connected members in original alignment after load is applied. Connections that comply with the requirements of Appendix P. the segment of a beam that is located between the ends of two diagonal braces or between the end of a diagonal brace and a column. Load and resistance factor design (LRFD). An OCBF in which a pair of diagonal braces located on one side of a column is connected to a single point within the clear column height. connecting elements. Vertical web stiffeners placed within the Link in EBF. A moment frame system that meets the requirements in Section 10.1. Joints are categorized by the type of fastener or weld used and the method of force transfer. or as appropriate) acting on a member or connection that is determined by structural analysis from the factored loads using the most appropriate critical load combinations. as determined by computations using specified material strengths and dimensions and formulas derived from accepted principles of structural mechanics or by field tests or laboratory tests of scaled models. Moment frame. Interstory displacement divided by story height. Link. Link intermediate web stiffeners. or as specified in these Provisions. Second-order effect of column axial loads after lateral deflection of the frame on the shears and moments in members.5 PART I Intermediate moment frame (IMF). K-braced frame. Interstory drift angle. In EBF. The lesser of the design shear strength of the Link developed from the moment or shear strength of the Link. Seismic design category. surfaces or edges are attached. A moment frame system that meets the requirements in Section 11. The load effect (force. Ordinary moment frame (OMF). radians. P . Resistance factor. An area where two or more ends. Inverted-V-braced frame. k-area. Ordinary concentrically braced frame (OCBF). A factor that accounts for unavoidable deviations in the actual strength of a member or connection from the Nominal Strength and for the manner and consequences of failure. Link shear design strength. A reduction in cross section over a discrete length that promotes a zone of inelasticity in the member. and assemblages) such that no applicable limit state is exceeded when the building is subjected to all appropriate load combinations. The length of the Link is defined as the clear distance between the ends of two diagonal braces or between the diagonal brace and the column face. Panel-zone. The capacity of a building or component to resist the effects of loads. A diagonally braced frame meeting the requirements in Section 14 in which all members of the bracing system are subjected primarily to axial forces. A classification assigned to a building based upon such factors as its occupancy 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . Required strength. A member that is designed to inhibit lateral buckling or lateral-torsional buckling of primary framing members. stress. The web area of the beam-to-column connection delineated by the extension of beam and column flanges through the connection. Reduced beam section. The magnitudes of the loads specified by the Applicable Building Code. connectors. Link rotation angle.
An assemblage of load-carrying components that are joined together to provide interaction or interdependence. A concentrically braced frame (OCBF) in which a pair of diagonal braces crosses near mid-length of the braces. Special concentrically braced frame (SCBF). Y-braced frame. Static yield strength. Where the diagonal braces are below the beam. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . diaphragms and trusses. Special moment frame (SMF). V-braced frame. PART I 6 and use. Special truss moment frame (STMF). including struts. Structural system. X-braced frame.3(b). chords. A bolted joint in which slip resistance on the faying surface(s) of the connection is required. A moment frame system that meets the requirements in Section 9. A vertical (or nearly vertical) strut connecting the brace-to-beam intersection of an inverted-V-braced frame at one level to the brace-to-beam intersection at another level. A diagonally braced frame meeting the requirements in Section 13 in which all members of the bracing system are subjected primarily to axial forces. Seismic load resisting system. Zipper column. Slip-critical joint. The strength of a structural member or connection that is determined on the basis of testing that is conducted under slow monotonic loading until failure. collectors. An Eccentrically Braced Frame (EBF) in which the stem of the Y is the Link of the EBF system. See Figure C-I-13. A concentrically braced frame (SCBF or OCBF) in which a pair of diagonal braces located either above or below a beam is connected to a single point within the clear beam span. The assembly of structural elements in the building that resists seismic loads. A truss moment frame system that meets the requirements in Section 12. the system is also referred to as an Inverted-V- Braced Frame.
and Sheet Piling. Zinc-Coated Welded and Seamless. December 27. November 10. 1999 Load and Resistance Factor Design Specification for the Design of Steel Hollow Structural Sections. and Appendices P. AND STANDARDS The documents referenced in these Provisions shall include those listed in LRFD Specification Section A6 with the following additions and modifications: American Concrete Institute (ACI) Building Code Requirements for Structural Concrete. REFERENCED SPECIFICATIONS. ASCE 7-02 American Society for Testing and Materials (ASTM) Standard Specification for General Requirements for Rolled Structural Steel Bars. ACI 318-02 American Institute of Steel Construction (AISC) Load and Resistance Factor Design Specification for Structural Steel Buildings. November 10. ASTM A325-01 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . ASTM A6/A6M-01 Standard Specification for Carbon Structural Steel.7 PART I 1. ASTM A283/A283M-00 Standard Specification for Structural Bolts. 2000 Load and Resistance Factor Design Specification for Single Angle Members. Part I includes a Glossary. These Provisions shall apply to buildings that are classified in the Applicable Building Code as Seismic Design Category D (or equivalent) and higher or when required by the Engineer of Record. Heat Treated. and shall also meet all of the additional requirements in these Provisions. Plates. All members and connections in the Seismic Load Resisting System shall have a design strength as required in the LRFD Specification. 120/105 ksi Minimum Tensile Strength. ASTM A53/A53M-01 Standard Specification for Low and Intermediate Tensile Strength Carbon Steel Plates. S. These Provisions shall be applied in conjunction with the AISC Load and Resistance Factor Design (LRFD) Specification for Structural Steel Buildings. CODES. Steel. ASTM A36/A36M-00 Pipe. and X. 2000 American Society of Civil Engineers (ASCE) Minimum Design Loads for Buildings and Other Structures. which is specifically applicable to this Part. Shapes. SCOPE These Provisions are intended for the design and construction of structural steel members and connections in the Seismic Load Resisting Systems in buildings for which the design forces resulting from earthquake motions have been determined on the basis of various levels of energy dissipation in the inelastic range of response. hereinafter referred to as the LRFD Specification. Black and Hot-Dipped. 2. Steel.
Loads and Load Combinations 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .1:2002 Research Council on Structural Connections Specification for Structural Joints Using ASTM A325 or A490 Bolts. ASTM A490M-00 Standard Specification for Cold-Formed Welded and Seamless Carbon Steel Structural Tubing in Rounds and Shapes. Produced by Quenching and Self-Tempering Process (QST). LOAD COMBINATIONS.9. 120/105 ksi Minimum Tensile Strength. AND NOMINAL STRENGTHS 4. ASTM F1852-00 American Welding Society Structural Welding Code – Steel. AWS D1.9 and 10. ASTM A913/A913M- 00a Standard Specification for Steel for Structural Shapes for Use in Building Framing. June 23. ASTM A490-00 Standard Specification for High-Strength Steel Bolts. Classes 10. LOADS. 2000 3. ASTM A325M-00 Standard Specification for Heat-Treated Steel Structural Bolts. Low Alloy Structural Tubing with Improved Atmospheric Corrosion Resistance. 4. PART I 8 Standard Specification for High-Strength Bolts for Structural Steel Joints [Metric].3. ASTM A529/A529M-00 Standard Specification for High-Strength Low-Allow Columbium-Vanadium Structural Steel. for Structural Steel Joints [Metric]. ASTM A588/A588M-00a Standard Specification for Hot-Formed Welded and Seamless High-Strength Low-Alloy Structural Tubing. Seismic Use Groups or Seismic Zones and the limitations on height and irregularity shall be as specified in the Applicable Building Code. ASTM A847- 99a Standard Specification for High-Strength Low-Allow Steel Shapes of Structural Quality. ASTM A992/A992M-00 Standard Specification for “Twist Off” Type Tension Control Structural Bolt/Nut/Washer Assemblies. ASTM A673/A673M-95 Standard Specification for Cold-formed Welded and Seamless High Strength. ASTM A618-01 Standard Specification for Sampling Procedure for Impact Testing of Structural Steel. ASTM A501-01 Standard Specification for High-Strength Carbon-Manganese Steel of Structural Quality. Heat Treated. [100 mm] Thick. GENERAL SEISMIC DESIGN REQUIREMENTS The required strength and other seismic provisions for Seismic Design Categories (SDCs). 150 ksi Minimum Tensile Strength. ASTM A500-01 Standard Specification for Hot-Formed Welded and Seamless Carbon Steel Structural Tubing. Steel.1. ASTM A572/A572M-00a Standard Specification for High-Strength Low-Allow Structural Steel with 50 ksi [345 MPa] Minimum Yield Point to 4 in.
the horizontal earthquake load E (as defined in the Applicable Building Code) shall be multiplied by the overstrength factor Ωo prescribed by the Applicable Building Code. MATERIALS 6. A913/A913M (Grade 50 (345) or 65 (450)). In the absence of a specific definition of Ωo. 14 and 15 shall meet one of the following ASTM Specifications: A36/A36M. A572/A572M (Grade 42 (290).1. A529/A529M. STORY DRIFT The Design Story Drift and story drift limits shall be determined as specified in the Applicable Building Code. Nominal Strength The nominal strength of systems. except as modified throughout these Provisions. For buildings over one story in height.9 PART I The loads and load combinations shall be as stipulated by the Applicable Building Code (see Glossary). 10. Ωo Seismic Load Resisting System Ωo All moment-frame systems meeting Part I requirements 3 Eccentrically Braced Frames (EBF) 2½ meeting Part I requirements All other systems meeting Part I requirements 2 4. TABLE I-4-1 System Overstrength Factor. 50 (345) or 55 (380)).2. the value for Ωo shall be as listed in Table I-4-1. 6. A501. 12. the steel used in the Seismic Load Resisting Systems described in Sections 9. members and connections shall meet the requirements in the LRFD Specification. A588/A588M. Material Specifications Structural steel used in the Seismic Load Resisting System shall meet the requirements in LRFD Specification Section A3. or A992/A992M. The steel used for column base plates shall meet one of the preceding ASTM specifications or ASTM A283/A283M Grade D.1a. A53/A53M. 11. 5. 13. A500 (Grade B or C). The specified minimum yield strength of steel to be used for members in which inelastic behavior is expected shall 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . except as modified in this Section. Where Amplified Seismic Loads are required by these provisions.
(38 mm) thick and thicker. For rolled shapes and bars. The bearing strength of bolted joints shall be provided using either standard holes or short-slotted holes with the slot perpendicular to the line of force. CONNECTIONS. Bolted Joints All bolts shall be pretensioned high-strength bolts.2. 4. ASTM A6/A6M Groups 3. the required strength of a connection or member shall be determined from the Expected Yield Strength RyFy. Ry shall be as given in Table I-6-1. 7. determined as specified in LRFD Specification Section A3. All faying surfaces shall be prepared as required for Class A or better slip-critical joints. and plates that are 2 in. see Appendix S. Bolted joints shall not be designed to share load in combination with welds on the same faying surface. of the connected member. The design shear strength of bolted joints is permitted to be calculated as that for bearing-type joints. except as modified in this Section.3. Other values of Ry are permitted to be used if the value of the Expected Yield Strength is determined by testing that is conducted in accordance with the requirements for the specified grade of steel. AND FASTENERS 7. JOINTS. 6. 7. joints and fasteners that are part of the Seismic Load Resisting System shall meet the requirements in LRFD Specification Chapter J. unless an alternative hole type is justified as part of a tested assembly. PART I 10 not exceed 50 ksi (345 MPa) unless the suitability of the material is determined by testing or other rational criteria. When both the required strength and the design strength calculations are made for the same member or connecting element. Material Properties for Determination of Required Strength When required in these Provisions. where Fy is the specified minimum yield strength of the grade of steel to be used. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .1. (50 mm) thick or thicker shall have a minimum Charpy V-Notch (CVN) toughness of 20 ft-lbs (27 J) at 70°F (21°C).2. it is permitted to apply Ry to Fy in the determination of the design strength.1c. Scope Connections. Notch-toughness Requirements When used as members in the Seismic Load Resisting System. 6. and 5 shapes with flanges 1½ in. This limitation does not apply to columns for which the only expected inelastic behavior is yielding at the column base.
3 Steel Pipe ASTM A53/A53M 1. A501.3a.1 Hollow Structural Sections ASTM A500.7 and J3.4 Plates 1.10.3 ASTM A992/A992M 1. as determined by AWS classification or manufacturer certification.1 All other grades 1. Welded Joints Welding shall be performed in accordance with a Welding Procedure Specification (WPS) as required in AWS D1.1 The design strength of bolted joints in shear and/or combined tension and shear shall be determined in accordance with LRFD Specification Sections J3. Additional Requirements in Special Moment Frames and Intermediate Moment Frames For structures in which the steel frame is normally enclosed and maintained at a temperature of 50°F (10°C) or higher. General Requirements All welds used in members and connections in the Seismic Load Resisting System shall be made with a filler metal that has a minimum Charpy V-notch toughness of 20 ft-lbs (27 J) at minus 20°F (minus 29°C).5 ASTM A572/A572M Grade 42 (290) 1. 7. A618 and A847 1. Bolted connections for members that are a part of the Seismic Load Resisting System shall be configured such that a ductile limit-state either in the connection or in the member controls the design. This requirement for notch toughness shall also apply in other cases as required in these Provisions.3.3b. the following CJP welds in special and intermediate moment frames shall be made with filler metal providing a minimum Charpy V-notch toughness of 20 ft-lbs (27 J) at minus 20°F (-29°C) as determined by 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .1 and approved by the Engineer of Record. The WPS variables shall be within the parameters established by the filler-metal manufacturer. 7. except that the nominal bearing strength at bolt holes shall not be taken greater than 2.11 PART I TABLE I-6-1 Ry Values for Different Member Types Application Ry Hot-rolled structural shapes and bars ASTM A36/A36M 1.4dtFu. 7.1 All other products 1.
The length of a plastic hinging zone shall be defined as one-half of the depth of the beam on either side of the theoretical hinge point. 7. shall be repaired as required by the Engineer of Record. Decking arc-spot welds as required to secure decking shall be permitted. screwed. Welded. (3) Column splices For structures with service temperatures lower than 50°F (10°C).1. Outside the expected zone of plastic deformation area. calculations. For members and connections that are part of the Seismic Load Resisting System. 8. partitions. or shot-in attachments for perimeter edge angles. or other construction shall not be placed within the expected zone of plastic deformations of members of the Seismic Load Resisting System. such as tack welds. bolted. see Section 8.2. shall be made to demonstrate the adequacy of the member net section when connectors that penetrate the member are used. Local Buckling 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . duct work. based on the expected moment. Exception: Welded shear studs and other connections are permitted where they have been included in the connection tests used to qualify the connection. 8. For members that are not part of the Seismic Load Resisting System.4c. discontinuities located within a plastic hinging zone defined below.4. exterior facades. and flame cutting. piping. Other Connections Welded shear studs shall not be placed on beam flanges within the zones of expected plastic hinging. erection aids. MEMBERS 8. PART I 12 AWS classification test methods and 40 ft-lbs (54 J) at 70°F (21°C) as determined by Appendix X or other approved method: (1) Welds of beam flanges to columns. Decking attachments that penetrate the beam flanges shall not be used in the plastic hinging zone. Scope Members in the Seismic Load Resisting System shall meet the requirements in the LRFD Specification and those of this Section. created by errors or by fabrication or erection operations. these qualification temperatures shall be reduced accordingly. (2) Groove welds of shear tabs and beam webs to columns. air-arc gouging.
members of the Seismic Load Resisting System shall meet the λp limitation in Table B5. (b) The limit as determined from the resistance of the foundation to overturning uplift. [e] Flanges of H-pile sections b/t 0.45 E s / Fy Flat bars[g] b/t 2. hybrid or welded b/t 0. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . b/t 0. [f]. Thickness Ratios ness λps Description of Element Ratio (seismically compact) Flanges of I-shaped rolled.30 E s / Fy hybrid or welded beams and braces [a].30 E s / Fy beams [a]. or flanges of tees [h] Webs of tees [h] d/t 0. Column Strength When Pu/φPn is greater than 0. [b].30 E s / Fy columns [a]. Unstiffened Elements [d].4 without consideration of the Amplified Seismic Load. considered in the absence of any applied moment. [c] Flanges of channels. hybrid or welded b/t 0. shall be determined using the load combinations stipulated by the Applicable Building Code including the Amplified Seismic Load. the following requirements shall be met: (1) The required axial compressive and tensile strength. angles and I-shaped rolled.30 E s / Fy 8. (2) The required strengths need not exceed either of the following: (a) The maximum load transferred to the column considering 1.1Ry times the nominal strengths of the connecting beam or brace elements of the building.1 in the LRFD Specification and the λps limitations of Table I-8-1. legs of double angle b/t 0.38 E s / Fy columns [a]. [h] Flanges of I-shaped rolled.5 Legs of single angle. [h] Flanges of I-shaped rolled.13 PART I Where required by these Provisions. TABLE I-8-1 Limiting Width Thickness Ratios λps for Compression Elements Width Limiting Width- Thick.30 E s / Fy members with separators. hybrid or welded b/t 0.3.
2 m) or more away from the beam-to-column connections. [c] Required for columns in SMF. Welded column splices that are subject to a calculated net tensile stress determined using the load combinations stipulated by the Applicable Building Code including the Amplified Seismic Load. Fy GH 2.94 E s / Fy [a] For hybrid beams. (1. [h] h/tw Webs of H-Pile sections h/tw 0. Section 12. 8. [f]. Column Splices 8. unless the ratios from [f] Required for link in EBF.64 E s / Fy compression [d]. use the yield strength of the flange Fyf instead of [e] It is permitted to use λp in LRFD Specification Table Fy. Section 9.4. Es F P I 112 .0 where it is permitted to use λp in [g] Diagonal web members within the special segment of LRFD Specification Table B5. Section 12.4a. [e].044 Es/Fy compression [d]. Section 12 and [b] Required for beams in SMF. General The required strength of column splices shall equal the required strength of the columns. [h] Chord members of STMF. [h] Rectangular HSS in axial and/or flexural b/t or 0. splices shall be at half the clear height.4 m).45 E s / Fy SMF. including that determined from Section 8.1 for columns in STMF. compression [a]. PART I 14 TABLE I-8-1 (cont. (2. [b]. [h] Es F Pu I 314 . unless noted otherwise [a] Other webs in flexural compression [a] h/tw 314 .33 − u φ b Py JK Round HSS in axial and/or flexural D/t 0. Equation 9-3 are greater than 2. [d]. Section 9. Section 9. B5. JK Stiffened Elements Fy φ b Py for Pu / φ b Py > 0125 . [d] Required for beams and braces in SCBF. Section 13. E s / Fy Webs in combined flexure and axial h/tw for Pu / φ b Py ≤ 0125 . STMF.3.) Limiting Width Thickness Ratios λps for Compression Elements Limiting Width- Width Thickness Ratios Thickness λps Description of Element Ratio (seismically compact) Webs in flexural compression in beams in h/tw 2. [c]. Section 15. Section 15. The centerline of column splices made with fillet welds or partial-joint-penetration groove welds shall be located 4 ft. shall be made using filler metal with Charpy V-notch 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . When the column clear height between beam-to-column connections is less than 8 ft. GH 1 − 154 . EBF.1.
4c. 8. Beveled transitions are not required when changes in thickness and width of flanges and webs occur in column splices where partial-joint-penetration groove welded joints are permitted.4 m). Design of H-Piles Design of H-piles shall comply with the provisions of the AISC LRFD Specification 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . Column Bases The connection of the structure frame elements to the column base and the connection of the column base to the foundations shall be adequate to transmit the forces for which the frame elements were required to be designed. Column Web Splices Column web splices shall be either bolted or welded.4b. 8. splices shall be at half the clear height.5 times RyFyAf. shall be in accordance with ACI 318. Columns Not Part of the Seismic Load Resisting System Splices of columns that are not a part of the Seismic Load Resisting System in moment frame buildings shall satisfy the following: (1) They shall be located 4 ft. (2. (2) The column splices shall have sufficient design shear strength with respect to both orthogonal axes of the column to resist a shear force equal to Mpc/H. The seismic loads to be transferred to the foundation soil interface shall be as required by the Applicable Building Code. In moment frames using bolted splices to develop the required strength.6. When the column clear height between beam-to-column connections is less than 8 ft. 8.15 PART I toughness as required in Section 7.6a. and H is the story height. 8. Design of concrete elements at the column base. or welded to one column and bolted to the other. (2) The design strength for each flange shall be at least 0. including anchor rod embedment and reinforcement steel. (1.2 m) or more away from the beam-to-column connections. where Mpc is the nominal plastic flexural strength of the column for the direction in question. H-Piles 8.3a and shall meet both of the following requirements: (1) The design strength of partial-joint-penetration groove welded joints shall be at least equal to 200 percent of the required strength.5. plates or channels shall be used on both sides of the column web. where RyFy is the Expected Yield Strength of the column material and Af is the flange area of the smaller column connected.
6c.6b. 8. must equal at least 80 percent of the nominal plastic moment of the connected beam at an Interstory Drift Angle of 0. 9. Scope Special Moment Frames (SMF) are expected to withstand significant inelastic deformations when subjected to the forces resulting from the motions of the Design Earthquake. Tension in H-Piles Tension in the pile shall be transferred to the pile cap by mechanical means such as shear keys. (3) The required shear strength Vu of the connection shall be determined using the load combination 1. PART I 16 regarding design of members subjected to combined loads. Alternatively. (2) The required flexural strength of the connection.04 radians.2D + 0. the vertical piles shall be designed to support combined effects of the dead and live loads without the participation of batter piles.1.2S plus the shear resulting from the application of a moment of 2[1. Beam-to-Column Joints and Connections 9. The width-thickness ratios of member elements shall meet the λps limitations of Table I-8-1. Requirements All beam-to-column joints and connections used in the Seismic Load Resisting System shall satisfy the following three requirements: (1) The connection must be capable of sustaining an Interstory Drift Angle of at least 0. A length of pile below the bottom of the pile cap equal to at least the overall depth of the pile cross section shall be free of attachments and welds.2a. provided it can be demonstrated by analysis that the additional drift due to connection 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . Batter H-Piles If batter (sloped) and vertical piles are used in a pile group. 8.2. Connections that accommodate the required Interstory Drift Angle within the connection elements and provide the required flexural and shear strengths noted above are permitted.1RyFyZ/distance between plastic hinge locations]. rebars or studs welded to the embedded portion of pile. SMF shall meet the requirements in this Section.04 radians. a lesser value of Vu is permitted if justified by analysis. SPECIAL MOMENT FRAMES (SMF) 9.5L + 0. determined at the column face. 9.
Shear Strength The required thickness of the panel zone shall be determined in accordance with the method used in proportioning the panel zone of the tested connection. (mm) bcf = width of the column flange. in. within the limits specified in Appendix S.17 PART I deformation can be accommodated by the building. material strengths. (mm) 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . Results of at least two cyclic connection tests shall be provided and are permitted to be based on one of the following: (i) Tests reported in research literature or documented tests performed for other projects that are demonstrated to represent project conditions. in.0.2a by one of the following: (a) Use a connection Prequalified for SMF in accordance with Appendix P. in. 9. As a minimum.6 F d t M1 + 2 cf cf (9-1) v y MN d d t PQ c p b c p where tp = total thickness of panel-zone including doubler plate(s). and matching connection processes. Such analysis shall include effects of overall frame stability including second order effects. within the limits specified in Appendix S. (b) Provide qualifying cyclic test results in accordance with Appendix S. Conformance Demonstration All beam-to-column joints and connections used in the Seismic Load Resisting System shall be demonstrated to satisfy the requirements of Section 9. (a) When Pu ≤ 0.3. Panel Zone of Beam-to-Column Connections (beam web parallel to column web) 9.75Py. 9.2b. (mm) tcf = thickness of the column flange. L 3b t OP R = 0. The design shear strength φvRv of the panel zone shall be determined using φv = 1. (mm) dc = overall column depth. the required shear strength Ru of the panel zone shall be determined from the summation of the moments at the column faces as determined by projecting the expected moments at the plastic hinge points to the column faces. connection configurations.3a. in. (ii) Tests that are conducted specifically for the project and are representative of project member sizes.
3c. in.2b.75Py. they shall be welded across the top and bottom edges to develop the proportion of the total force that is transmitted to the doubler plate. shall conform to the following requirement: t> _ (dz + wz)/90 (9-2) where t = thickness of column web or doubler plate. the total panel-zone thickness shall satisfy Equation 9-2. Beam and Column Limitations Abrupt changes in beam flange area are not permitted in plastic hinge regions. When doubler plates are placed against the column web.5. Ry shall be calculated using LRFD Specification Equation K1- 12. (mm) Fy = specified minimum yield strength of the panel-zone steel. Where employed. Continuity Plates Continuity plates shall be provided to match the tested connection. if used. 9. (mm) wz = panel-zone width between column flanges. the Reduced Beam Section shall meet the required strength as specified in Section 9. when local buckling of the column web and doubler plate is prevented with plug welds between them. When doubler plates are placed away from the column web. The drilling of flange holes or trimming of beam flange width is permitted if testing demonstrates that the resulting configuration can develop stable plastic hinges that meet the requirements in Section 9.2a(2). they shall be placed symmetrically in pairs and welded to continuity plates to develop the proportion of the total force that is transmitted to the doubler plate. Beams and columns shall satisfy the width-thickness limitations given in Table I-8-1. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . Panel-Zone Doubler Plates Doubler plates shall be welded to the column flanges using either a complete-joint- penetration groove-welded or fillet-welded joint that develops the design shear strength of the full doubler plate thickness. PART I 18 db = overall beam depth. (mm) dz = panel-zone depth between continuity plates. in. Panel-Zone Thickness The individual thicknesses t of column webs and doubler plates. ksi (MPa) (b) When Pu > 0. in. in. 9.3b. 9. 9.4. (mm) Alternatively.
Ag = gross area of column.4. It is permitted to take ΣM*pc = ΣZc(Fyc- Puc/Ag). in. it is permitted to take ΣM*pb = Σ(1. kips (a positive number) (N) Zc = plastic section modulus of the column.1RyMp+Mv). in.3 (mm3) Exception: When columns conform to the requirements in Section 9. where z is the minimum plastic section modulus at the Reduced Beam Section. (ii) Columns where: (1) the sum of the design shear strengths of all exempted columns in the story is less than 20 percent of the required story shear 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .3FycAg for all load combinations other than those determined using the Amplified Seismic Load that meet either of the following requirements: (i) Columns used in a one-story building or the top story of a multistory building. it is permitted to determine ΣM*pb from test results as required in Section 9. It is permitted to take ΣM*pb = Σ(1. this requirement does not apply in the following two cases: (a) Columns with Puc < 0.2 (mm2) Fyc = specified minimum yield strength of column. where Mv is the additional moment due to shear amplification from the location of the plastic hinge to the column centerline. ΣM*pb = the sum of the moment(s) in the beam(s) at the intersection of the beam and column centerlines.1RyFyz+Mv).6.2b or by analysis based upon the tests. ksi (MPa) Puc = required column axial compressive strength. Column-Beam Moment Ratio The following relationship shall be satisfied at beam-to-column connections: ΣM *pc > 10 . Alternatively. ΣM*pc is determined by summing the projections of the nominal flexural strengths of the column (including haunches where used) above and below the joint to the beam centerline with a reduction for the axial force in the column. ΣM*pb is determined by summing the projections of the expected beam flexural strength(s) at the plastic hinge location(s) to the column centerline. the mid-line between centerlines shall be used. When connections with Reduced Beam Sections are used. (9-3) ΣM *pb where ΣM*pc = the sum of the moments in the column above and below the joint at the intersection of the beam and column centerlines. When the centerlines of opposing beams in the same joint do not coincide.19 PART I 9.
PART I 20 strength. a column line is defined as a single line of columns or parallel lines of columns located within 10 percent of the plan dimension perpendicular to the line of columns. For the purpose of this exception. (2) Each column-flange lateral bracing shall be designed for a required strength that is equal to 2 percent of the nominal beam flange strength (Fybftbf). except that: (1) The required column strength shall be determined from the LRFD Specification. by means of the column web or by the flanges of perpendicular beams.7. (b) 125 percent of the frame design strength based upon either the beam design flexural strength or panel-zone design shear strength. (2) The slenderness L/r for the column shall not exceed 60. 9.7b. Restrained Connections Column flanges at beam-to-column connections require lateral bracing only at the level of the top flanges of the beams when a column is shown to remain elastic outside of the panel-zone. the following requirements shall apply: (1) The column flanges shall be laterally supported at the levels of both the top and bottom beam flanges. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . (3) Column flanges shall be laterally supported.7a. When a column cannot be shown to remain elastic outside of the panel-zone. and (2) the sum of the design shear strengths of all exempted columns on each column line within that story is less than 33 percent of the required story shear strength on that column line. 9. Unrestrained Connections A column containing a beam-to-column connection with no lateral bracing transverse to the seismic frame at the connection shall be designed using the distance between adjacent lateral braces as the column height for buckling transverse to the seismic frame and shall conform to LRFD Specification Chapter H. except that E shall be taken as the lesser of: (a) The Amplified Seismic Load. Beam-to-Column Connection Restraint 9. either directly or indirectly. (b) Columns in any story that have a ratio of design shear strength to required shear strength that is 50 percent greater than the story above. It shall be permitted to assume that the column remains elastic when the ratio calculated using Equation 9-3 is greater than 2.
10.8. the placement of lateral bracing for the beams shall be consistent with that used in the tests.3b. 10.4a. column splices in Special Moment Frames shall be located as described in Section 8. Exception: The required strength of the column splice considering appropriate stress concentration factors or fracture mechanics stress intensity factors need not exceed that determined by inelastic analyses.9. they shall be complete-joint-penetration groove welds.086ryEs/Fy. The required stiffness of all lateral bracing shall be determined in accordance with Equation C3-8 or C3-10.21 PART I (3) The column required flexural strength transverse to the seismic frame shall include that moment caused by the application of the beam flange force specified in Section 9. changes in cross- section and other locations where analysis indicates that a plastic hinge will form during inelastic deformations of the SMF. The unbraced length between lateral braces shall not exceed 0. Mu shall be computed as RyZFy. INTERMEDIATE MOMENT FRAMES (IMF) 10. Lateral Bracing of Beams Both flanges of beams shall be laterally braced directly or indirectly. Weld tabs shall be removed. of the LRFD Specification.1 Scope Intermediate Moment Frames (IMF) are expected to withstand limited inelastic deformations in their members and connections when subjected to the forces resulting from the motions of the Design Earthquake. Steel backing need not be removed unless required by the Engineer of Record. as applicable. In these equations. IMF shall meet the requirements in this Section. and shall have a required flexural strength that is at least equal to Ry times the design flexural strength of the smaller column. Where groove welds are used to make the splice.4 and 7. The required shear strength of column web splices shall be at least equal to 2Mpc/H.7(1)(b) in addition to the second-order moment due to the resulting column flange displacement. The required strength of lateral bracing shall be at least 2 percent of the beam flange nominal strength. Where the design is based upon assemblies tested in accordance with Appendix S. 9. Column Splices Column splices shall comply with the requirements in Sections 8. In addition. Beam-to-Column Joints and Connections 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . 9. In addition.2. Fybftf. lateral braces shall be placed near concentrated forces. The required strength of lateral bracing provided adjacent to plastic hinges shall be at least 6 percent of the expected nominal strength of the beam flange computed as RyFybftf.
within the limits specified in Appendix S. PART I 22 10. (2) The flexural strength of the connection. Panel-Zone of Beam-to-Column Connections (beam web parallel to column web) No additional requirements beyond the AISC LRFD Specification. provided it can be demonstrated by analysis that the additional drift due to connection deformation can be accommodated by the building.2D + 0. and matching connection processes.2b. (b) Provide qualifying cyclic test results in accordance with Appendix S. (3) The required shear strength Vu of the connection shall be determined using the load combination 1. within the limits specified in Appendix S.02 radians. a lesser value of Vu is permitted if justified by analysis.2S plus the shear resulting from the application of 2[1. The required shear strength need not exceed the shear resulting from the application of Load Combinations using the Amplified Seismic Load.1RyFyZ/ distance between plastic hinge segments]. Conformance Demonstration All beam-to-column joints and connections used in the Seismic Load Resisting System shall be demonstrated to satisfy the requirements of Section 10.02 radians. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .5L + 0.3. by one of the following: (a) Use a connection prequalified for IMF in accordance with Appendix P. Connections that accommodate the required Interstory Drift Angle within the connection elements and provide the required flexural and shear strengths noted above are permitted. 10. Such analysis shall include effects of overall frame stability including second order effects. (ii) Tests that are conducted specifically for the project and are representative of project member sizes. 10. Requirements All beam-to-column joints and connections used in the Seismic Load Resisting System shall satisfy the following three requirements: (1) The connection must be capable of sustaining an Interstory Drift Angle of at least 0. material strengths. must equal at least 80 percent of the nominal plastic moment of the connected beam at an Interstory Drift Angle of 0. determined at the column face. Alternatively. Results of at least two non-identical cyclic connection tests shall be provided and are permitted to be based on one of the following: (i) Tests reported in research literature or documented tests performed for other projects that are demonstrated to represent project conditions. connection configurations.2a.2a.
ORDINARY MOMENT FRAMES (OMF) 11. Connections are permitted to be FR or PR moment connections as follows: (1) FR moment connections that are part of the Seismic Load Resisting System shall be designed for a required flexural strength Mu that is at least equal to 1. Column-Beam Moment Ratio No additional requirements beyond the AISC LRFD Specification.4 and 7. Scope Ordinary Moment Frames (OMF) are expected to withstand minimal inelastic deformations in their members and connections when subjected to the forces resulting from the motions of the Design Earthquake. 10. 10.2.8. 11. Beam-to-Column Joints and Connections Beam-to-column connections shall be made with welds and/or high-strength bolts. 10. (a) Where steel backing is used in connections with complete-joint-penetration (CJP) flange welds. 10. Lateral Bracing of Beams No additional requirements beyond the AISC LRFD Specification.1RyMp of the beam or girder or the maximum moment that can be delivered by the system. steel backing and tabs shall be removed except that top- flange backing attached to the column by a continuous fillet weld on the edge below the CJP groove weld need not be removed. Continuity Plates Continuity plates shall be provided to be consistent with the tested connection.4. 11.5.7.9. 10. the root pass shall be backgouged to sound weld metal and backwelded with a reinforcing fillet. OMF shall meet the requirements in this Section.1. whichever is less. The 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . Column Splices Column splices shall comply with the requirements in Sections 8.6.3b. Removal of steel backing and tabs shall be as follows: (i) Following the removal of backing. Beam and Column Limitations No additional requirements beyond the AISC LRFD Specification. Beam-to-Column Connection Restraint No additional requirements beyond the AISC LRFD Specification.23 PART I 10.
(1) above. (6 mm) of the plate edge is acceptable. The transitional slope of any area where gouges and notches have been removed shall not exceed 1:5. (c) Double-sided partial-joint-penetration groove welds and double-sided fillet welds that resist tensile forces in connections shall be designed to resist a required force of 1.2D + 0. (b) The nominal flexural strength of the connection. Mn.3 Panel-Zone of Beam-to-Column Connections (beam web parallel to column web) No additional requirements beyond the AISC LRFD Specification. Edges of the weld tab shall be finished to a surface roughness value of 500 micro-in. (2) PR moment connections are permitted when the following requirements are met: (a) Such connections shall provide for the design strength as specified in Section 11. (ii) Weld tab removal shall extend to within 1/8 in. Alternatively. (13 micrometers). Gouges and notches are not permitted. the required shear strength Vu of a beam-to-column connection shall be determined using the load combination 1. (b) Where weld access holes are provided. Vu shall be determined from the load combination above plus the shear resulting from the maximum end moment that the PR moment connections are capable of resisting. (3 mm) of the base metal surface except at continuity plates where removal to within ¼ in.5L + 0. shall be no less than 50 percent of Mp of the connected beam or column. Single-sided partial-joint-penetration groove welds and single-sided fillet welds shall not be used to resist tensile forces in the connections. Grinding to a flush condition is not required. free of notches and sharp corners.1RyFyZ / distance between plastic hinge segments]. (2 mm) below the surface of the base metal shall be filled with weld metal. and shall be free of notches and gouges. they shall be as shown in Figure 11-1. 11. including the effect on overall frame stability. (13 micrometers) or better. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . (c) The stiffness and strength of the PR moment connections shall be considered in the design. a lesser value of Vu is permitted if justified by analysis.2a. (8 mm). Notches and gouges shall be repaired as required by the Engineer of Record. For FR moment connections. The contour of the weld at the ends shall provide a smooth transition.1RyFyAg of the connected element or part. For PR moment connections. Material removed by grinding that extends more than 1/16 in. whichever is less. PART I 24 reinforcing fillet shall have a minimum leg size of 5/16-in.2S plus the shear resulting from the application of a moment of 2[1. The weld access hole shall be ground smooth to a surface roughness value not to exceed 500 micro in.
(b) The design shear strength of the contact area of the plate with the column web. (d) The actual force transmitted by the stiffener.5 Continuity Plates When FR moment connections are made by means of welds of beam flanges or beam- flange connection plates directly to column flanges. (c) The weld design strength that develops the design shear strength of the column panel-zone. continuity plates shall be provided to transmit beam flange forces to the column web or webs. two-sided partial-joint-penetration groove welds combined with reinforcing fillet welds. The welded joints of the continuity plates to the column flanges shall be made with either complete-joint-penetration groove welds. The required strength of the welded joints of the continuity plates to the column web shall be the least of the following: (a) The sum of the design strengths at the connections of the continuity plate to the column flanges.25 PART I 11. The required strength of these joints shall not be less than the design strength of the contact area of the plate with the column flange. 11.4 Beam and Column Limitations No additional requirements beyond the AISC LRFD Specification. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . or two-sided fillet welds. Plates shall have a thickness greater than or equal to that of the beam flange or beam-flange connection plate.
Weld access hole detail (from FEMA 350. 11-1. (13 mm) (plus ½ tbf. ¾ in. Larger of tbf or ½ in. PART I 26 Notes: 1. Fig.) (±13 mm) Tolerances shall not accumulate to the extent that the angle of the access hole cut to the flange surface exceeds 25°. Bevel as required by AWS D1. 3 tbf (± ½ in. “Recommended Seismic Design Criteria for New Steel Moment-Frame Buildings”).1 for selected groove weld procedure. ¾ tbf to tbf. (19 mm) minimum (± ¼ in. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . 2. (10 mm) minimum radius (plus not limited.) (± 6 mm) 4. minus 0) 5. or minus ¼ tbf) 3. 3/8 in.
neither a combination thereof nor the use of other truss diagonal configurations is permitted. 12. SPECIAL TRUSS MOMENT FRAMES (STMF) 12. 11.67. Where diagonal members are used in the special segment.6 Column-Beam Moment Ratio No additional requirements beyond the AISC LRFD Specification.4.03FyAg. STMF shall be limited to span lengths between columns not to exceed 65 ft (20 m) and overall depth not to exceed 6 ft (1.27 PART I 11. Scope Special Truss Moment Frames (STMF) are expected to withstand significant inelastic deformation within a specially designed segment of the truss when subjected to the forces from the motions of the Design Earthquake. 12. Splicing of chord members is not permitted within the special segment. The columns and truss segments outside of the special segments shall be designed to remain elastic under the forces that can be generated by the fully yielded and strain- hardened special segment.9 Column Splices Column splices shall comply with the requirements in Section 8. 12.7 Beam-to-Column Connection Restraint No additional requirements beyond the AISC LRFD Specification. Axial forces due to factored dead plus live loads in diagonal web members within the special segment shall not exceed 0. Bolted connections shall not be used for web members within the special segment. 11.8 Lateral Bracing of Beams No additional requirements beyond the AISC LRFD Specification. 11. The interconnection shall have a design strength adequate to resist a force that is at least equal to 0. nor within one-half the panel length from the ends of the special segment.2. Nominal Strength of Special Segment Members 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . STMF shall meet the requirements in this Section. Such diagonal members shall be interconnected at points where they cross. Special Segment Each horizontal truss that is part of the Seismic Load Resisting System shall have a special segment that is located between the quarter points of the span of the truss.3.8 m). The length-to- depth ratio of any panel in the special segment shall neither exceed 1.5 nor be less than 0. Panels within a special segment shall either be all Vierendeel panels or all X-braced panels.25 times the nominal tensile strength of the diagonal member.1. The length of the special segment shall be between 0. they shall be arranged in an X pattern separated by vertical members.1 and 0.5 times the truss span length.
Lateral Bracing The top and bottom chords of the trusses shall be laterally braced at the ends of special segment. in. (mm) Ls = length of the special segment. RyFyAg.45 times φFyAg.9. where φ = 0. 12. see Section 6. when provided. kip-in.4.3P sin α y ( nt nc ) Vne = + 0. shall have a design strength to resist the effects of load combinations stipulated by the Applicable Building Code. PART I 28 In the fully yielded state.075Es I (12-1) Ls L3s where Ry = yield stress modification factor.5. kips (N) Pnc = nominal axial compression strength of diagonal members of the special segment. (mm) Pnt = nominal axial tension strength of diagonal members of the special segment. Nominal Strength of Non-special Segment Members Members and connections of STMF.6. Diagonal web members within the special segment shall be made of flat bars. kip-in. replacing the earthquake load term E with the lateral loads necessary to develop the expected vertical nominal shear strength in the special segment Vne given as: 3. the special segment shall develop the required vertical shear strength through the design flexural strength of the chord members and the design axial tensile and compressive strengths of the diagonal web members. 12. (N-mm) EsI = flexural elastic stiffness of the chord members of the special segment. Diagonal members in any panel of the special segment shall be made of identical sections.2. The end connection of diagonal web members in the special segment shall have a design strength that is at least equal to the expected nominal axial tensile strength of the web member. in. along the entire length of the truss. except those in the special segment defined in Section 12.2 Mnc = nominal flexural strength of the chord member of the special segment. kips (N) α = angle of diagonal members with the horizontal 12. and at intervals not to exceed Lp according to LRFD Specification Section F1. The top and bottom chord members in the special segment shall be made of identical sections and shall provide at least 25 percent of the required vertical shear strength in the fully yielded state.2 (N-mm2) L = span length of the truss.75 Ry M nc ( L − Ls ) + R P + 0. Compactness The width-thickness ratio of chord members shall not exceed the limiting λps values from Table I-8-1. The required strength of each lateral brace at the ends 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . The required axial strength in the chord members shall not exceed 0.
1.5 percent of the nominal compressive strength Pnc of the largest adjoining chord member. 13. Scope 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . Lateral braces outside of the special segment shall have a required strength at least 2. SPECIAL CONCENTRICALLY BRACED FRAMES (SCBF) 13.29 PART I of and within the special segment shall be at least 5 percent of the nominal axial compressive strength Pnc of the special segment chord member.
1 (i. 13.2. SCBF shall meet the requirements in this Section. Width-thickness Ratios Width-thickness ratios of stiffened and unstiffened compression elements of braces shall meet the compactness requirements in LRFD Specification Table B5. For the purposes of this provision.2a. Lateral Force Distribution Along any line of bracing.2e. Built-up Members The spacing of stitches shall be such that the slenderness ratio l/r of individual elements between the stitches does not exceed 0.2c. Slenderness Bracing members shall have Kl/r ≤5. SCBF have increased ductility over OCBF (see Section 14) due to lesser strength degradation when compression braces buckle.2d. 13.87 Es / Fy .2b.4 times the governing slenderness ratio of the built- up member. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . a line of bracing is defined as a single line or parallel lines whose plan offset is 10 percent or less of the building dimension perpendicular to the line of bracing. Bracing Members 13. (3) Round HSS shall have an outside diameter to wall thickness ratio conforming to Table I-8-1 unless the round HSS wall is stiffened. for either direction of force parallel to the bracing. braces shall be deployed in alternate directions such that. 13.e. 13. (4) Rectangular HSS shall have a flat width to wall thickness ratio conforming to Table I-8-1 unless the rectangular HSS walls are stiffened. Required Compressive Strength The required strength of a bracing member in axial compression shall not exceed φcPn. 13. unless the nominal strength Pn of each brace in compression is larger than the required strength Pu resulting from the application of load combinations stipulated by the Applicable Building Code including the Amplified Seismic Load. PART I 30 Special Concentrically Braced Frames (SCBF) are expected to withstand significant inelastic deformations when subjected to the forces resulting from the motions of the Design Earthquake. λ<λp) and the following requirements: (1) The width-thickness ratio of angle legs shall comply with λps in Table I-8-1.. (2) I-shaped members and channels shall comply with λps in Table I-8-1. at least 30 percent but no more than 70 percent of the total horizontal force is resisted by tension braces.
3b. Flexural Strength In the direction that the brace will buckle.3b.3d.4a. the required flexural strength of the connection shall be equal to 1. The spacing of stitches shall be uniform and not less than two stitches shall be used. V-Type and Inverted-V-Type Bracing V-type and inverted-V-type braced frames shall meet the following requirements: 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . indicated by analysis that can be transferred to the brace by the system.3c. Gusset Plates The design of gusset plates shall include consideration of buckling. 13. can accommodate the inelastic rotations associated with brace post-buckling deformations. Required Strength The required strength of bracing connections (including beam-to-column connections if part of the bracing system) shall be the lesser of the following: (a) The nominal axial tensile strength of the bracing member.3a. 13. 13. Bracing Connections 13.3. and have a design strength that is at least equal to the nominal compressive strength FcrAg of the brace are permitted. shall be at least equal to the required strength of the brace as determined in Section 13. 13. Special Bracing Configuration Requirements 13. Exception: Where it can be shown that braces will buckle without causing shear in the stitches. as specified in LRFD Specification Section J4.1RyMp of the brace about the critical buckling axis. Bolted stitches shall not be located within the middle one-fourth of the clear brace length. determined as RyFyAg.75 times the governing slenderness ratio of the built-up member. based upon the limit states of tension rupture on the effective net section and block shear rupture strength. 13. the spacing of the stitches shall be such that the slenderness ratio l/r of the individual elements between the stitches does not exceed 0. Tensile Strength The design tensile strength of bracing members and their connections. (b) The maximum force.3a.31 PART I The total design shear strength of the stitches shall be at least equal to the design tensile strength of each element. Exception: Brace connections that meet the requirements in Section 13.4.
column splices in SCBF shall be designed to develop at least the nominal shear strength of the smaller connected member and 50 percent of the nominal flexural strength of the smaller connected section. Strength 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . 14.5. PART I 32 (1) A beam that is intersected by braces shall be continuous between columns. one-story buildings. 14. 13. OCBF shall meet the requirements in this Section. This load effect shall be calculated using a minimum of RyPy for the brace in tension and a maximum of 0. ORDINARY CONCENTRICALLY BRACED FRAMES (OCBF) 14. K-Type Bracing K-type braced frames are not permitted for SCBF. Qb is the maximum unbalanced vertical load effect applied to the beam by the braces. Splices shall be located in the middle one-third of the column clear height.2.4. Columns Columns in SCBF shall meet the following requirements: Width-thickness ratios of stiffened and unstiffened compression elements of columns shall meet the requirements for bracing members in Section 13. 13.4b. except that a load Qb shall be substituted for the term E. (3) A beam that is intersected by braces shall be designed to resist the effects of load combinations stipulated by the Applicable Building Code.2d.1. (4) The top and bottom flanges of the beam at the point of intersection of braces shall be designed to support a lateral force that is equal to 2 percent of the nominal beam flange strength Fybftbf. nor the top story of buildings. Scope Ordinary Concentrically Braced Frames (OCBF) are expected to withstand limited inelastic deformations in their members and connections when subjected to the forces resulting from the motions of the Design Earthquake. (2) A beam that is intersected by braces shall be designed to support the effects of all tributary dead and live loads from load combinations stipulated by the Applicable Building Code. In addition to meeting the requirements in Section 8. Exception: Limitations 2 and 3 need not apply to penthouses.3 times φcPn for the brace in compression.
If the required axial strength Pu in a Link exceeds 0. Links Links shall comply with the width-thickness ratios in Table I-8-1.1.15Py. EBF shall meet the requirements in this Section. except where permitted in this Section. The diagonal braces. determined as Ry Fy Ag. In buildings exceeding five stories in height. the required shear strength of the Link Vu shall not exceed the design shear strength of the Link φVn.33 PART I The required strength of the members and connections. Scope Eccentrically Braced Frames (EBFs) are expected to withstand significant inelastic deformations in the Links when subjected to the forces resulting from the motions of the Design Earthquake. ECCENTRICALLY BRACED FRAMES (EBF) 15.6FyAw. equal to the lesser of Vp or 2Mp/e. other than brace connections. The specified minimum yield stress of steel used for Links shall not exceed 50 ksi (345 MPa) The web of a Link shall be single thickness without doubler-plate reinforcement and without web penetrations. where: 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . (mm) Aw = (db-2tf)tw If the required axial strength Pu in a Link is equal to or less than 0. the following additional requirements shall be met: (1) The Link design shear strength shall be the lesser of φVpa or 2φMpa/e. 15. the columns. kips (N) e = Link length. in OCBFs shall be determined using the load combinations stipulated by the Applicable Building Code. including the Amplified Seismic Load.2. the effect of axial force on the Link design shear strength need not be considered.23 E s / Fy shall not be used in V or inverted-V configurations.15Py. The required strength of brace connections is the expected tensile strength of the brace. the upper story of an EBF system is permitted to be designed as an OCBF or an SCBF and still be considered to be part of an EBF system for the purposes of determining system factors in the Applicable Building Code.9 Vn = Nominal shear strength of the Link. Except as limited below. and the beam segments outside of the Links shall be designed to remain essentially elastic under the maximum forces that can be generated by the fully yielded and strain-hardened Links. kips (N) Vp = 0. Braces with Kl/r greater than 4. where Py is equal to FyAg. in. 15. where: φ = 0.
6Mp/Vp when ρ' (Aw/Ag) > _ 0. M p 1 − Pu / Py h (15-2) (2) The length of the Link shall not exceed: [1.6Mp/Vp or greater. These stiffeners shall have a combined width not less than (bf .3. ∆.6Mp/Vp and 2.08 and 0.6Mp/Vp or less shall be provided with intermediate web stiffeners spaced at intervals not exceeding (30tw-d/5) for a Link Rotation Angle of 0.6Mp/Vp and less than 5Mp/Vp shall be provided with intermediate web stiffeners placed at a distance of 1.75tw nor 3/8 in. where bf and tw are the Link flange width and Link web thickness.08 radians or (52tw-d/5) for Link Rotation Angles of 0.02 radians. (c) Links of length between 1.02 radians or less.6Mp/Vp or less.15 .0.6Mp/Vp. respectively. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . (10 mm). The Link Rotation Angle shall not exceed the following values: (a) 0. Link Stiffeners Full-depth web stiffeners shall be provided on both sides of the Link web at the diagonal brace ends of the Link. (b) 0. Linear interpolation shall be used for values between 0. (b) Links of length greater than 2. (c) The value determined by linear interpolation between the above values for Links of length between 1. whichever is larger.5ρ′(Aw/Ag)]1.5 times bf from each end of the Link. Links shall be provided with intermediate web stiffeners as follows: (a) Links of lengths 1.6Mp/Vp and 2.6 Mp/Vp when ρ′(Aw/Ag) < 0. 15. PART I 34 φ = 0.2tw) and a thickness not less than 0.3. (15-4) where: Aw = (db .3.6Mp/Vp shall be provided with intermediate web stiffeners meeting the requirements of 1 and 2 above.2tf)tw ρ′ = Pu/Vu The Link Rotation Angle is the inelastic angle between the Link and the beam outside of the Link when the total story drift is equal to the Design Story Drift. (15-3) nor 1.08 radians for Links of length 1.9 c Vpa = Vp 1 − Pu / Py h 2 (15-1) M pa = 118 c .02 radians for Links of length 2.
Exception: Where reinforcement at the beam-to-column connection at the Link end precludes yielding of the beam over the reinforced length. the Link is permitted to be the beam segment from the end of the reinforcement to the brace connection. within the limits specified in Appendix S. For Links that are 25 in. The strength of the connection. (b) Provide qualifying cyclic test results in accordance with Appendix S.4. Results of at least two cyclic connection tests shall be provided and are permitted to be based on one of the following: (i) Tests reported in research literature or documented tests performed for other projects that are demonstrated to represent project conditions. (ii) Tests that are conducted specifically for the project and are representative of project member sizes. (635 mm) in depth. and the width shall be not less than (bf/2)-tw. (10 mm). The required strength of fillet welds connecting a Link stiffener to the Link web is AstFy. where Ast is the area of the stiffener. (635 mm) in depth or greater. The thickness of one-sided stiffeners shall not be less than tw or 3/8 in. similar intermediate stiffeners are required on both sides of the web. cyclic testing of the reinforced connection is not required if the design strength of the reinforced section and the connection equals or exceeds the required strength calculated based upon the strain- hardened Link as described in Section 15. Lateral Bracing of Link Lateral bracing shall be provided at both the top and bottom Link flanges at the ends of the 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . Link-to-Column Connections Link-to-column connections must be capable of sustaining the maximum Link Rotation Angle based on the length of the link. measured at the column face. 15. For Links that are less than 25 in. and matching connection processes. Vn. whichever is larger. Link-to-column connections shall be demonstrated to satisfy the above requirements by one of the following: (a) Use a connection Prequalified for EBF in accordance with Appendix P. within the limits specified in Appendix S. must equal at least the nominal shear strength of the link. stiffeners are required on only one side of the Link web. connection configurations.3a shall be placed at the Link-to-reinforcement interface. 15.5. Full depth stiffeners as required in Section 15.35 PART I (d) Intermediate web stiffeners are not required in Links of lengths greater than 5Mp/Vp.6Mp/Vp.6. material strengths. The required strength of fillet welds fastening the stiffener to the flanges is AstFy/4. Where such Links are used and the Link length does not exceed 1.2. as specified in Section 15. as specified in Section 15. (e) Intermediate Link web stiffeners shall be full depth.2 at the maximum Link Rotation Angle.
the required strength of columns shall be determined from load combinations as stipulated by the Applicable Building Code. the connection shall be designed as an FR moment connection. 15. The width-thickness ratio of the brace shall satisfy λp in LRFD Specification Table B5. (2) The beam shall be provided with lateral bracing where analysis indicates that support is necessary to maintain the stability of the beam. 15. it is permitted to multiply the design strengths determined from the LRFD Specification by Ry.2.8. where Vn is as defined in Section 15.6. The required strength of end lateral bracing of Links is 6 percent of the expected nominal strength of the Link flange computed as RyFybftf.1 times the expected nominal shear strength of the Link RyVn. The design strengths of the diagonal brace. PART I 36 Link. The required strength of the diagonal brace-to-beam connection at the Link end of the brace shall be at least the expected nominal strength of the brace as given in Section 15. the intersection of the brace and beam centerlines shall be at the end of the Link or in the Link. The design of the beam outside the Link shall meet the following requirements: (1) The required strength of the beam outside of the Link shall be the forces generated by at least 1. except that the moments and axial loads introduced into the column at the connection of a Link or brace shall not be less than those generated by the expected nominal strength of the Link 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . Lateral bracing shall be provided at both the top and bottom flanges of the beam and each shall have a required strength of at least 2 percent of the beam flange nominal strength computed as Fybftf. The connection shall have a required strength to resist rotation about the longitudinal axis of the beam based upon two equal and opposite forces of at least 2 percent of the beam flange nominal strength computed as Fybftf acting laterally on the beam flanges.7.2. 15. At the connection between the diagonal brace and the beam at the Link end of the brace.1. Diagonal Brace and Beam Outside of Link The required combined axial and flexural strength of the diagonal brace shall be the axial forces and moments generated by the expected nominal shear strength of the Link RyVn increased by 125 percent to account for strain-hardening. as determined in LRFD Specification Chapter H (including Appendix H3). If the brace resists a portion of the Link end moment. For determining the design strength of this portion of the beam. where Vn is as defined in Section 15. No part of this connection shall extend over the Link length.6. shall exceed the required strengths as defined above. Required Column Strength In addition to the requirements in Section 8. Beam-to-Column Connections Beam-to-column connections away from Links are permitted to be designed as pinned in the plane of the web.
1 to account for strain-hardening. such as participation in a recognized quality certification program. using approved nondestructive methods conforming to AWS D1. Visual inspections shall be conducted by qualified personnel. materials and workmanship incorporated in construction are those that have been specified and approved for the project. When welds from web doubler plates or continuity plates occur in the k-area of rolled steel columns. 12.2d. 11. shall be considered when establishing a quality control plan.1 shall also be performed. 16. 10.1. (2) All complete-joint-penetration and partial-joint-penetration groove welded joints that are subjected to net tensile forces as part of the Seismic Load Resisting Systems in Sections 9. The special inspections and tests necessary to establish that the construction is in conformance with these Provisions shall be included in a quality assurance plan. where Vn is as defined in Section 15. Exception: The amount of nondestructive testing is permitted to be reduced if approved by the Engineer of Record and the Authority Having Jurisdiction. but shall not serve to replace visual inspection. as required by the Engineer of Record. 14 and 15 shall be tested using approved nondestructive methods conforming to AWS D1. the k-area adjacent to the welds shall be inspected after fabrication. The expected nominal strength of the Link is RyVn. Nondestructive testing of welds in conformance with AWS D1. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .1. QUALITY ASSURANCE The general requirements and responsibilities for performance of a quality assurance plan shall be in accordance with the requirements of the Authority Having Jurisdiction and the specifications of the Engineer of Record. 13. in accordance with a written practice.37 PART I multiplied by 1. The contractor’s quality control program and qualifications. The minimum special inspection and testing contained in the quality assurance plan beyond that required in LRFD Specification Section M5 shall be as follows: (1) Visual inspection of welding shall be the primary method used to confirm that the procedures.
strength and deformation capacity of the connection and the Seismic Load Resisting System must be identified. PART I 38 APPENDIX P PREQUALIFICATION OF BEAM-COLUMN AND LINK- TO-COLUMN CONNECTIONS P1. A sufficient number of tests shall be performed on enough non-identical specimens to demonstrate that the connection has the ability and reliability to undergo the required Interstory Drift Angle for SMFs and IMFs and the required Link Rotation Angle for EBFs. The effect of design variables listed in Section P4 shall be addressed for connection prequalification. stability related limit states. SCOPE This appendix contains minimum requirements for prequalification of beam-to-column moment connections in Special Moment Frames (SMFs) and Intermediate Moment Frames (IMFs). Authority for Prequalification Prequalification of a connection and the associated limits of prequalification shall be established by a Connection Prequalification Review Panel (CPRP) approved by the Authority Having Jurisdiction.1. additional 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . and the limits of prequalification are being changed. GENERAL REQUIREMENTS P2. Basis for Prequalification Connections shall be Prequalified based on test data satisfying Section P3.2. where the link is adjacent to columns. P2. TESTING REQUIREMENTS Data used to support connection prequalification shall be based on tests conducted in accordance with Appendix S. within the applicable limits of prequalification. and all other limit states pertinent for the connection under consideration. All applicable limit states for the connection that affect the stiffness. P3. The combined body of evidence for prequalification must be sufficient to assure that the connection can supply the required Interstory Drift Angle for SMF and IMF systems. and link-to-column connections in Eccentrically Braced Frames (EBFs). P2. Prequalified connections are permitted to be used. These include fracture related limit states. The CPRP shall also provide the same information when limits are to be changed for a previously prequalified connection. supported by analytical studies and design models. without the need for further qualifying cyclic tests. or the required Link Rotation Angle for EBFs. The CPRP shall determine the number of tests and the variables considered by the tests for connection prequalification. For connections that are already Prequalified Connections. on a consistent and reliable basis within the specified limits of prequalification.
(e) Weight per foot. (i) Lateral bracing. (j) Other parameters pertinent to the specific connection under consideration. (b) Thickness. beam or link is connected to column web. PREQUALIFICATION VARIABLES In order to be Prequalified. or other. (5) Welds: (a) Weld type: CJP. (2) Column parameters: (a) Cross-section shape: wide flange. (3) Beam (or Link) – Column Relations: (a) Panel zone strength. (h) Width-thickness ratio of cross-section elements. (1) Beam or Link parameters: (a) Cross-section shape: wide flange. (h) Width thickness ratio of cross-section elements. (g) Material specification. (d) Weight per foot. or plug. (d) Depth. or link length (for EBF). (c) Depth. (4) Continuity plates: (a) Identification of conditions under which continuity plates are required. or other. welded shape. (f) Flange thickness. (b) Doubler plate attachment details. Limits on the permissible values for each variable shall be established by the CPRP for the Prequalified Connection. the effect of the following variables on connection performance shall be considered.39 PART I non-identical specimens shall be tested prior to changing prequalification limits. (g) Span-to-depth ratio (for SMF or IMF). (i) Lateral bracing.2. box. welded shape. PJP. or other. (b) Cross-section fabrication method: rolled shape. (c) Column-beam (or link) moment ratio. (c) Attachment details. beams or links are connected to both the column flange and web. width and depth. box. Section S5. (c) Column orientation with respect to beam or link: beam or link is connected to column flange. or other. fillet. or other. (e) Flange thickness. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . (b) Cross-section fabrication method: rolled shape. (j) Other parameters pertinent to the specific connection under consideration. P4. (f) Material specification. The limits on member sizes for prequalification shall not exceed the limits specified in Appendix S.
(f) Other parameters pertinent to the specific connection under consideration. snug tight. P6. punching. (6) Bolts: (a) Bolt diameter. (b) Bolt Grade: ASTM A325. oversize. or other. (d) Hole type: standard. (f) Other parameters pertinent to the specific connection under consideration. intended location(s) of inelastic action. (2) Description of the expected behavior of the connection in the elastic and inelastic ranges of behavior. PART I 40 (b) Filler metal strength and toughness. (c) Installation requirements: pretensioned. A490. or other. geometry and finish. P5. as established by the CPRP. (3) Listing of systems for which connection is Prequalified: SMF. (7) Summary of material strengths (8) Summary of quality control procedures. (5) A detailed description of the design procedure for the connection. (6) A list of references of test reports. sub-punching and reaming. The design procedure must address all applicable limit states within the limits of prequalification. (7) Additional Connection Details: All variables pertinent to the specific connection under consideration. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . research reports and other publications that provided the basis for prequalification. as required in Section P5. or other. DESIGN PROCEDURE A comprehensive design procedure must be available for a Prequalified Connection. (e) Hole fabrication method: drilling. (d) Weld access holes: size. PREQUALIFICATION RECORD A Prequalified Connection shall be provided with a written prequalification record with the following information: (1) General description of the Prequalified Connection and drawings that clearly identify key features and components of the connection. (e) Welding quality control and quality assurance. short-slot. IMF or EBF. or other. (c) Details and treatment of weld backing and weld tabs. long-slot. and a description of limit states controlling the strength and deformation capacity of the connection. (4) Listing of limits for all prequalification variables listed in Section P4.
Alternative testing requirements are permitted when approved by the Engineer of Record and the Authority Having Jurisdiction. The permanent or plastic portion of the rotation angle between a beam and the column or between a Link and the column of the Test Specimen. additional testing shall be performed to demonstrate satisfactory and reliable performance of moment connections during actual earthquake motions. S2. and slip between members and connection elements. inelastic rotation shall be computed based upon the assumption that inelastic action is concentrated at a single point located at the intersection of the 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . Interstory drift angle. DEFINITIONS Complete loading cycle. For link-to-column connections in Eccentrically Braced Frames. Interstory displacement divided by story height. yielding of connection elements and connectors. If conditions in the actual building so warrant. The purpose of the testing described in this Appendix is to provide evidence that a beam-to-column connection or a link-to- column connection satisfies the requirements for strength and Interstory Drift Angle or Link Rotation Angle in these Provisions.41 PART I APPENDIX S QUALIFYING CYCLIC TESTS OF BEAM-TO-COLUMN AND LINK-TO-COLUMN CONNECTIONS S1. measured in radians. SCOPE AND PURPOSE This Appendix includes requirements for qualifying cyclic tests of beam-to-column moment connections in Moment Frames and Link-to-column connections in Eccentrically Braced Frames. A cycle of rotation taken from zero force to zero force. inelastic rotation shall be computed based upon the assumption that inelastic action is concentrated at a single point located at the intersection of the centerline of the beam with the centerline of the column. SYMBOLS The numbers in parentheses after the definition of a symbol refers to the Section number in which the symbol is first used. including one positive and one negative peak. For beam-to-column moment connections in Moment Frames. Inelastic rotation. θ Interstory drift angle (S6) γ Link rotation angle (S6) S3. Sources of inelastic rotation include yielding of members. This Appendix provides only minimum recommendations for simplified test conditions. radians. when required in these Provisions. The Inelastic Rotation shall be computed based on an analysis of Test Specimen deformations.
Size of Members 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . Sources of Inelastic Rotation Inelastic Rotation shall be developed in the Test Specimen by inelastic action in the same members and connection elements as anticipated in the Prototype.1. Additional lateral bracing of the Test Subassemblage is not permitted.e. S5. Prototype. Test setup. and other design. S4. detailing. unless it replicates lateral bracing to be used in the Prototype. (2) Points of inflection in the test assemblage shall coincide approximately with the anticipated points of inflection in the Prototype under earthquake loading. ESSENTIAL TEST VARIABLES The Test Specimen shall replicate as closely as is practical the pertinent design. Test subassemblage. TEST SUBASSEMBLAGE REQUIREMENTS The Test Subassemblage shall replicate as closely as is practical the conditions that will occur in the Prototype during earthquake loading. The connections. or within connection elements. member sizes. steel properties.2. in the column outside of the panel-zone. in the beam or Link. The following variables shall be replicated in the Test Specimen. The fraction of the total Inelastic Rotation in the Test Specimen that is developed in each member or connection element shall be at least 75 percent of the anticipated fraction of the total Inelastic Rotation in the Prototype that is developed in the corresponding member or connection element. Test specimen. A portion of a frame used for laboratory testing. PART I 42 centerline of the link with the face of the column. loading equipment. and construction features to be used in the actual building frame. The supporting fixtures. S5. and material properties of the Prototype. construction features. i. S5. The Test Subassemblage shall include the following features: (1) The Test Specimen shall consist of at least a single column with beams or Links attached to one or both sides of the column. The combination of the Test Specimen and pertinent portions of the Test Setup.. detailing. and lateral bracing used to support and load the Test Specimen. in the column panel-zone. (3) Lateral bracing of the Test Subassemblage is permitted near load application or reaction points as needed to provide lateral stability of the Test Subassemblage. intended to model the Prototype.
The use of yield stress values that are reported on certified mill test reports are not permitted to be used for purposes of this Section. Connection Details The connection details used in the Test Specimen shall represent the Prototype connection details as closely as possible. S5. RyFy shall be determined in accordance with Section 6.4. The connection elements used in the Test Specimen shall be a full-scale representation of the connection elements used in the Prototype. S5. (2) The weight per foot of the test beam or Link shall be no less than 75 percent of the weight per foot of the Prototype beam or Link.5. (2) The yield stress of the beam shall not be more than 15 percent below RyFy for the grade of steel to be used for the corresponding elements of the Prototype. The size of the column used in the Test Specimen shall properly represent the inelastic action in the column. Columns and connection elements with a tested yield stress shall not be more than 15 percent above or below RyFy for the grade of steel to be used for the corresponding elements of the Prototype. the depth of the test column shall be no less than 90 percent of the depth of the Prototype column.43 PART I The size of the beam or Link used in the Test Specimen shall be within the following limits: (1) The depth of the test beam or Link shall be no less than 90 percent of the depth of the Prototype beam or Link. S5.6. In addition. Welds The welds on the Test Specimen shall replicate the welds on the Prototype as closely as practicable. Additionally. Continuity Plates The size and connection details of continuity plates used in the Test Specimen shall be proportioned to match the size and connection details of continuity plates used in the Prototype connection as closely as possible. Material Strength The following additional requirements shall be satisfied for each member or connection element of the Test Specimen that supplies Inelastic Rotation by yielding: (1) The yield stress shall be determined by material tests on the actual materials used for the Test Specimen. for the member sizes being tested.1.2. S5. Extrapolation beyond the limitations stated in this Section shall be permitted subject to qualified peer review and approval by the Authority Having Jurisdiction. welds on the Test Specimen shall satisfy the following 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . as per the requirements in Section S5.3. as specified in Section S8.
S6. S5. LOADING HISTORY S6.g. or other) used in the Test Specimen shall be the same as those to be used for the corresponding bolt holes in the Prototype. (5) Details of weld backing.7. (3) When Inelastic Rotation is to be developed either by yielding or by slip within a bolted portion of the connection. Class A. bolted portions of the Test Specimen shall satisfy the following requirements: (1) The bolt grade (e. (4) The welding positions used to make the welds on the Test Specimen shall be the same as those to be used for the Prototype welds. The WPS essential variables shall meet the requirements in AWS D1.1. General Requirements 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . ASTM F1852) used in the Test Specimen shall be the same as that to be used for the Prototype.1 and shall be within the parameters established by the filler-metal manufacturer. the method used to make the bolt holes (drilling. or C slip resistance. PART I 44 requirements: (1) Welding shall be performed in strict conformance with Welding Procedure Specifications (WPS) as required in AWS D1. B. long slot. or other) as that to be used for the corresponding bolts in the Prototype.. Bolts The bolted portions of the Test Specimen shall replicate the bolted portions of the Prototype connection as closely as possible.1. ASTM A490. sub-punching and reaming. Additionally. (6) Methods of inspection and nondestructive testing and standards of acceptance used for Test Specimen welds shall be the same as those to be used for the Prototype welds. short slot. access holes. (2) The type and orientation of bolt holes (standard. (4) Bolts in the Test Specimen shall have the same installation (pretensioned or other) and faying surface preparation (no specified slip resistance. oversize. (2) The specified minimum tensile strength of the filler metal used for the Test Specimen shall be the same as that to be used for the corresponding Prototype welds. ASTM A325. Weld backing and weld tabs shall not be removed from the Test Specimen welds unless the corresponding weld backing and weld tabs are removed from the Prototype welds. and similar items used for the Test Specimen welds shall be the same as those to be used for the corresponding Prototype welds. (3) The specified minimum CVN toughness of the filler metal used for the Test Specimen shall not exceed the specified minimum CVN toughness of the filler metal to be used for the corresponding Prototype welds. or other) in the Test Specimen shall be the same as that to be used in the corresponding bolt holes in the Prototype. weld tabs.
Continue loading at increments of θ = 0.04 rad. imposed on the Test Specimen. θ. γ.04 rad. imposed on the Test Specimen.01 rad. (6) 2 cycles at θ = 0. (2) 6 cycles at θ = 0. S8.005 rad.2 for beam-to-column moment connections in Moment Frames. as follows: (1) 3 cycles at γ = 0.2.01 radians. (4) 4 cycles at θ = 0.015 rad. with two cycles of loading at each step.01 rad. (7) 2 cycles at θ = 0. (6) 2 cycles at γ = 0.02 rad.45 PART I The Test Specimen shall be subjected to cyclic loads according to the requirements prescribed in Section S6. (4) 2 cycles at γ = 0. S6. (3) 6 cycles at θ =0.0025 rad. Loading Sequence for Beam-to-Column Moment Connections Qualifying cyclic tests of beam-to-column moment connections in Moment Frames shall be conducted by controlling the interstory drift angle. INSTRUMENTATION Sufficient instrumentation shall be provided on the Test Specimen to permit measurement or calculation of the quantities listed in Section S9.3. and according to the requirements prescribed in Section S6. (5) 2 cycles at γ = 0.00375 rad. MATERIALS TESTING REQUIREMENTS 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . Loading sequences other than those specified in Sections S6. (3) 3 cycles at γ = 0.0075 rad. (5) 2 cycles at θ = 0. Continue loading at increments of γ = 0.03 rad. S6. Loading Sequence for Link-to-Column Connections Qualifying cyclic tests of link-to-column moment connections in Eccentrically Braced Frames shall be conducted by controlling the link rotation angle.03 rad.3 for link-to-column connections in Eccentrically Braced Frames.2 and S6. (8) 2 cycles at θ = 0.3 may be used when they are demonstrated to be of equivalent or greater severity. S7.01 radians.005 rad. with two cycles of loading at each step. as follows: (1) 6 cycles at θ = 0.02 rad. (2) 3 cycles at γ = 0.
PART I 46
S8.1. Tension Testing Requirements
Tension testing shall be conducted on samples of steel taken from the material adjacent to
each Test Specimen. Tension-test results from certified mill test reports shall be reported
but are not permitted to be used in place of specimen testing for the purposes of this
Section. Tension-test results shall be based upon testing that is conducted in accordance
with Section S8.2. Tension testing shall be conducted and reported for the following
portions of the Test Specimen:
each Test Specimen. Tension-test results from certified mill test reports shall be reported
but are not permitted to be used in place of specimen testing for the purposes of this
Section. Tension-test results shall be based upon testing that is conducted in accordance
with Section S8.2. Tension testing shall be conducted and reported for the following
portions of the Test Specimen:
(1) Flange(s) and web(s) of beams and columns at standard locations.
(2) Any element of the connection that supplies Inelastic Rotation by yielding.
S8.2. Methods of Tension Testing
Tension testing shall be conducted in accordance with ASTM A6/A6M, ASTM A370, and
ASTM E8, with the following exceptions:
ASTM E8, with the following exceptions:
(1) The yield stress Fy that is reported from the test shall be based upon the yield
strength definition in ASTM A370, using the offset method at 0.002 strain.
strength definition in ASTM A370, using the offset method at 0.002 strain.
(2) The loading rate for the tension test shall replicate, as closely as practical, the loading
rate to be used for the Test Specimen.
rate to be used for the Test Specimen.
S9. TEST REPORTING REQUIREMENTS
For each Test Specimen, a written test report meeting the requirements of the Authority
Having Jurisdiction and the requirements of this Section shall be prepared. The report shall
thoroughly document all key features and results of the test. The report shall include the
following information:
Having Jurisdiction and the requirements of this Section shall be prepared. The report shall
thoroughly document all key features and results of the test. The report shall include the
following information:
(1) A drawing or clear description of the Test Subassemblage, including key dimensions,
boundary conditions at loading and reaction points, and location of lateral braces.
boundary conditions at loading and reaction points, and location of lateral braces.
(2) A drawing of the connection detail showing member sizes, grades of steel, the sizes
of all connection elements, welding details including filler metal, the size and
location of bolt holes, the size and grade of bolts, and all other pertinent details of the
connection.
of all connection elements, welding details including filler metal, the size and
location of bolt holes, the size and grade of bolts, and all other pertinent details of the
connection.
(3) A listing of all other Essential Variables for the Test Specimen, as listed in Section
S5.
S5.
(4) A listing or plot showing the applied load or displacement history of the Test
Specimen.
Specimen.
(5) A plot of the applied load versus the displacement of the Test Specimen. The
displacement reported in this plot shall be measured at or near the point of load
application. The locations on the Test Specimen where the loads and
2002 Seismic Provisions
AMERICAN INSTITUTE OF STEEL CONSTRUCTION
displacement reported in this plot shall be measured at or near the point of load
application. The locations on the Test Specimen where the loads and
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AMERICAN INSTITUTE OF STEEL CONSTRUCTION
47 PART I
displacements were measured shall be clearly indicated.
(6) A plot of beam moment versus interstory drift angle for beam-to-column moment
connections; or a plot of link shear force versus link rotation angle for link-to-
column connections. For beam-to-column connections, the beam moment and the
interstory drift angle shall be computed with respect to the centerline of the
column.
connections; or a plot of link shear force versus link rotation angle for link-to-
column connections. For beam-to-column connections, the beam moment and the
interstory drift angle shall be computed with respect to the centerline of the
column.
(7) The Interstory Drift Angle and the total Inelastic Rotation developed by the Test
Specimen. The components of the Test Specimen contributing to the total
Inelastic Rotation due to yielding or slip shall be identified. The portion of the
total Inelastic Rotation contributed by each component of the Test Specimen shall
be reported. The method used to compute Inelastic Rotations shall be clearly
shown.
Specimen. The components of the Test Specimen contributing to the total
Inelastic Rotation due to yielding or slip shall be identified. The portion of the
total Inelastic Rotation contributed by each component of the Test Specimen shall
be reported. The method used to compute Inelastic Rotations shall be clearly
shown.
(8) A chronological listing of significant test observations, including observations of
yielding, slip, instability, and fracture of any portion of the Test Specimen as
applicable.
yielding, slip, instability, and fracture of any portion of the Test Specimen as
applicable.
(9) The controlling failure mode for the Test Specimen. If the test is terminated prior to
failure, the reason for terminating the test shall be clearly indicated.
failure, the reason for terminating the test shall be clearly indicated.
(10) The results of the material tests specified in Section S8.
(11) The Welding Procedure Specifications (WPS) and welding inspection reports.
Additional drawings, data, and discussion of the Test Specimen or test results are permitted
to be included in the report.
to be included in the report.
S10. ACCEPTANCE CRITERIA
The Test Specimen must satisfy the strength and Interstory Drift Angle or Link Rotation
Angle requirements of these Provisions for the SMF, IMF, or EBF connection, as
applicable. The Test Specimen must sustain the required Interstory Drift Angle or Link
Rotation Angle for at least one complete loading cycle.
Angle requirements of these Provisions for the SMF, IMF, or EBF connection, as
applicable. The Test Specimen must sustain the required Interstory Drift Angle or Link
Rotation Angle for at least one complete loading cycle.
2002 Seismic Provisions
AMERICAN INSTITUTE OF STEEL CONSTRUCTION
AMERICAN INSTITUTE OF STEEL CONSTRUCTION
PART I 48
APPENDIX X
WELD METAL / WELDING PROCEDURE
SPECIFICATION TOUGHNESS VERIFICATION TEST
Preamble: This appendix provides a procedure for qualifying the weld metal toughness and is
included on an interim basis pending adoption of such a procedure by AWS or other
accredited organization.
WELD METAL / WELDING PROCEDURE
SPECIFICATION TOUGHNESS VERIFICATION TEST
Preamble: This appendix provides a procedure for qualifying the weld metal toughness and is
included on an interim basis pending adoption of such a procedure by AWS or other
accredited organization.
X1. Scope
This appendix provides a standard method for qualification testing of weld filler metals
required to have specified notch toughness for service in specified joints in steel
moment frames for seismic applications.
required to have specified notch toughness for service in specified joints in steel
moment frames for seismic applications.
Testing of weld metal to be used in production shall be performed by filler metal
manufacturer's production lot, as defined in AWS A5.01, Filler Metal Procurement
Guidelines, as follows:
manufacturer's production lot, as defined in AWS A5.01, Filler Metal Procurement
Guidelines, as follows:
(1) Class C3 for SMAW electrodes,
(2) Class S2 for GMAW-S and SAW electrodes,
(3) Class T4 for FCAW and GMAW-C, or
(4) Class F2 for SAW fluxes.
Alternatively, filler metal manufacturers approved for production of products meeting the
above requirements, under a program acceptable to the Engineer, need not conduct the
mechanical A5 tests or the Weld Metal / Weld Procedure Specification (WPS) Toughness
Verification Test, or require lot control for each lot, and may rely upon the Manufacturer's
certifications that the product meets the specified performance requirements.
above requirements, under a program acceptable to the Engineer, need not conduct the
mechanical A5 tests or the Weld Metal / Weld Procedure Specification (WPS) Toughness
Verification Test, or require lot control for each lot, and may rely upon the Manufacturer's
certifications that the product meets the specified performance requirements.
X2. Test Conditions
Tests shall be conducted at the range of heat inputs for which the weld filler metal will
be qualified under the WPS. It is recommended that tests be conducted at the Low Heat
Input Level and High Heat Input Level indicated in Table I-X-1.
be qualified under the WPS. It is recommended that tests be conducted at the Low Heat
Input Level and High Heat Input Level indicated in Table I-X-1.
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AMERICAN INSTITUTE OF STEEL CONSTRUCTION
AMERICAN INSTITUTE OF STEEL CONSTRUCTION
shall fall within the range of heat inputs and interpass temperatures tested. Standard Methods for Mechanical Testing of Welds. Should it be necessary to interrupt welding. except that machined tensile test specimens may be aged at 200°F (93°C) to 220°F (104°C) for up to 48 hours. X3. Welding shall continue until the assembly has reached the interpass temperature prescribed in Table I-X-1. Regardless of the method of selecting test heat input. No thermal treatment of weldment or test specimens is permitted. then cooled to room temperature before testing. The test plate and specimens shall be as shown in Figure 2A in AWS A5. the WPS. The test assembly shall be restrained during welding.20-95. The interpass temperature shall be maintained for the remainder of the weld. or 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . or preset at approximately 5 degrees to prevent warpage in excess of 5 degrees. Each plate shall be steel. as used by the contractor. and five Charpy V-notch (CVN) test specimens shall be made per plate. CVN specimens shall be prepared in accordance with AWS B4. Test Specimens Two test plates. Two of the remaining three values shall equal. in order to minimize dilution effects.29-98.0-92. The assembly shall then be heated to the prescribed interpass temperature before welding is resumed. of any AISC- listed structural grade. or as in Figure 5 in AWS A5.2 kJ/mm) 70 ± 25 (21 ± 14) 200 ± 50 (93 ± 28) High Heat Input Test 80 kJ/in. A welded test assembly that has warped more than 5 degrees shall be discarded. the assembly shall be allowed to cool in air. the filler metal manufacturer or Contractor may elect to test a wider or narrower range of heat inputs and interpass temperatures. measured by temperature indicating crayons or surface temperature thermometers one inch from the center of the groove at the location shown in the figures cited above. (19 mm) thick with a 1/2-inch (13 mm) root opening and 45° included groove angle. Section A3. The test assembly shall be tack welded and heated to the specified preheat temperature. All test specimens shall be taken from near the centerline of the weld at the mid-thickness location.1 kJ/mm) 300 ± 25 (149 ± 14) 500 ± 50 (260 ± 28) Alternatively. X4. The range of heat inputs and interpass temperatures tested shall be clearly stated on the test reports and user data sheets. one for each heat input level shall be used. (3. a minimum of two passes per layer shall be used to fill the width. Except for the root pass. Welded test assemblies shall not be straightened. (1.49 PART I Table I-X-l WPS Toughness Verification Test Welding and Preheat Conditions Cooling Rate Heat Input Preheat °F (°C) Interpass °F (°C) Low Heat Input Test 30 kJ/in. Acceptance Criteria The lowest and highest CVN toughness values obtained from the five specimens from a single test plate shall be disregarded. The test plate shall be 3/4 in.
the specified toughness of 40 ft-lbf (54 J) energy level at the testing temperature. and the average of the three shall not be less than the required 40 ft-lbf (54 J) energy level. One of the three may be lower. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . All test samples shall meet the notch toughness requirements for the electrodes as provided in Section 7.3b. but not lower than 30 ft-lbf (41 J). PART I 50 exceed.
Composite beam. A concrete slab that is supported on and bonded to a formed steel deck and that acts as a diaphragm to transfer force to and between elements of the Seismic Force Resisting System. Encased composite beam. Portion along wall and diaphragm edges strengthened with structural steel sections and/or longitudinal steel reinforcement and transverse reinforcement. Coupling beam. Boundary member. A structural steel beam that is either an unencased steel beam that acts integrally with a concrete or composite slab using shear connectors or a fully reinforced-concrete- encased steel beam. Member that serves to transfer forces between floor diaphragms and the members of the Seismic Force Resisting System. Partially composite beam. Composite slab. Reinforcement in composite members that is designed and detailed to resist the required loads. A composite beam that has a sufficient number of shear connectors to develop the nominal plastic flexural strength of the composite section. A structural steel column (rolled or built-up) that is completely encased in reinforced concrete. A wall that consists of a steel plate with reinforced concrete encasement on one or both sides that provides out-of-plane stiffening to prevent buckling of the steel plate.concrete shear wall. An unencased composite beam with a nominal flexural strength that is controlled by the strength of the shear stud connectors. Collector element. A reinforced-concrete-encased structural steel section (rolled or built-up)or concrete-filled steel section that is used as a column. Partially restrained composite connection. Composite column. Load-carrying reinforcement. A reinforced concrete wall that has unencased or reinforced-concrete- encased structural steel sections as Boundary Members. Composite plate . Concrete-filled composite column. The plates are located at the face of the reinforced concrete to provide confinement and to transfer forces to the concrete through direct bearing. Partially restrained connections as defined in the LRFD 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . Stiffeners that are attached to structural steel beams that are embedded in reinforced concrete walls or columns. A structural steel or composite beam that connects adjacent reinforced concrete wall elements so that they act together to resist lateral forces. A structural steel beam that is completely encased in reinforced concrete that is cast integrally with the slab and for which full composite action is provided by bond between the structural steel and reinforced concrete. Fully composite beam. Face bearing plates. Composite brace. Round or rectangular structural steel section that is filled with concrete.51 PART II Part II—Composite Structural Steel and Reinforced Concrete Buildings Glossary The following glossary terms are applicable to Part II are in addition to those given in the Part Glossary. Composite shear wall. Encased composite column. A reinforced-concrete-encased structural steel section (rolled or built-up) or concrete-filled steel section that is used as a brace.
but is provided to facilitate the erection of other steel reinforcement and to provide anchorage for stirrups or ties. Restraining bars. Reinforced-concrete-encased shapes. such reinforcement is not spliced to be continuous. Structural steel sections that are encased in reinforced concrete. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . Steel reinforcement in composite members that is not designed to carry required forces. PART II 52 Specification that connect partially or fully composite beams to steel columns with flexural resistance provided by a force couple achieved with steel reinforcement in the slab and a steel seat angle or similar connection at the bottom flange. Generally.
the stiffness properties of the component members of composite systems shall reflect their condition at the onset of significant yielding of the building. except as modified in these provisions. AND STANDARDS The documents referenced in these provisions shall include those listed in Part I Section 2 with the following additions and modifications: American Society of Civil Engineers Standard for the Structural Design of Composite Slabs. CODES. 2.53 PART II 1. hereinafter referred to as the LRFD Specification. Provisions shall be applied in conjunction with the AISC Load and Resistance Factor Design (LRFD) Specification for Structural Steel Buildings. REFERENCED SPECIFICATIONS. LOADS. 4. AND NOMINAL STRENGTHS The loads and load combinations shall be as stipulated by the Applicable Building Code (see Glossary). which is specifically applicable to this Part. The applicable requirements in Part I shall be used for the design of structural steel components in composite systems. ASCE 3-91 3. Reinforced-concrete members subjected to seismic forces shall meet the requirements in ACI 318. SCOPE These Provisions are intended for the design and construction of composite structural steel and reinforced concrete members and connections in the Seismic Load Resisting Systems in buildings for which the design forces resulting from earthquake motions have been determined on the basis of various levels of energy dissipation in the inelastic range of response. When the design is based upon elastic analysis. Part II includes a Glossary. The Part I Glossary is also applicable to Part II. All members and connections in the Seismic Load Resisting System shall have a design strength as required in the LRFD Specification and shall meet the requirements in these Provisions. Seismic Use Groups or Seismic Zones and the limitations on height and irregularity shall be as stipulated in the Applicable Building Code . Where Amplified Seismic Loads are required by these provisions. In the absence of a specific 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . SEISMIC DESIGN CATEGORIES The required strength and other seismic provisions for Seismic Design Categories. the horizontal earthquake load E (as defined in the Applicable Building Code) shall be multiplied by the overstrength factor Ωo prescribed by the Applicable Building Code. LOAD COMBINATIONS.
MATERIALS 5.1 Scope The design of composite members in the Seismic Load Resisting Systems described in Sections 8 through 17 shall meet the requirements in this Section and the material requirements in Section 5. 13. f′’c shall not be taken as greater than 10 ksi (69 MPa) for normal-weight concrete nor 4 ksi (28 MPa) for lightweight concrete. Structural steel used in the composite Seismic Force Resisting Systems described in Sections 8. and the following requirements: (1) The specified minimum compressive strength of concrete in composite members shall equal or exceed 2. Ωo Seismic Load Resisting System Ωo All moment-frame systems meeting Part II requirements 3 All Eccentrically Braced Frames (EBF) 2½ and wall systems meeting Part II requirements All other systems meeting Part II requirements 2 definition of Ωo.1. the value for Ωo shall be as listed in Table II-4-1. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .2. PART II 54 TABLE II-4-1 System Overstrength Factor. 6. Structural Steel Structural steel used in composite Seismic Load Resisting Systems shall meet the requirements in LRFD Specification Section A3. 13.1a. Concrete and Steel Reinforcement Concrete and steel reinforcement used in composite Seismic Load Resisting Systems shall meet the requirements in ACI 318. 16. 14. 5. excluding Chapters 21 and 22. and 17 shall also meet the requirements in ACI 318 Chapter 21. Concrete and steel reinforcement used in the composite Seismic Load Resisting Systems described in Sections 8. COMPOSITE MEMBERS 6. 5. 14. (2) For the purposes of determining the nominal strength of composite members. 16 and 17 shall also meet the requirements in Part I Section 6. 9.5 ksi (17 MPa). 9.
ksi (MPa) (2) Beam flanges shall meet the requirements in Part I Section 9. except when fully reinforced-concrete-encased compression elements have a reinforced concrete cover of at least 2 in.55 PART II 6. Composite slab diaphragms shall meet the requirements in this Section. Collector Elements. the composite diaphragm design shear strength shall be determined by in- plane shear tests of concrete-filled diaphragms. and elements of the horizontal framing system. 6. Such columns shall meet the requirements in LRFD 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . ksi (MPa) Es = modulus of elasticity of the steel beam. The nominal shear strength of composite diaphragms and concrete-filled steel deck diaphragms shall be taken as the nominal shear strength of the reinforced concrete above the top of the steel deck ribs in accordance with ACI 318 excluding Chapter 22.3. in. 700 Fy 1+ Es where Ycon = distance from the top of the steel beam to the top of concrete. in.3. (mm) db = depth of the steel beam. Details shall be designed to transfer forces between the diaphragm and Boundary Members. Composite beams that are part of C-SMF as described in Section 9 shall also meet the following requirements: (1) The distance from the maximum concrete compression fiber to the plastic neutral axis shall not exceed: Ycon + db (6-1) 1. Composite Floor and Roof Slabs The design of composite floor and roof slabs shall meet the requirements of ASCE 3.4. Composite Beams Composite beams shall meet the requirements in LRFD Specification Chapter I. (50 mm) and confinement is provided by hoop reinforcement in regions where plastic hinges are expected to occur under seismic deformations.4. 6.1. (mm) Fy = specified minimum yield strength of the steel beam. Reinforced-concrete-encased Composite Columns This Section is applicable to columns that: (1) consist of reinforced-concrete-encased structural steel sections with a structural steel area that comprises at least 4 percent of the total composite-column cross-section. and (2) meet the additional limitations in LRFD Specification Section I2.3. Alternatively. Hoop reinforcement shall meet the requirements in ACI 318 Section 21.2.
Columns that consist of reinforced-concrete-encased structural steel sections with a structural steel area that comprises less than 4 percent of the total composite-column cross- section shall meet the requirements for reinforced concrete columns in ACI 318 except as modified for: (1) The steel shape shear connectors in Section 6. shear connectors shall be provided to transfer the force 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .4a. Additional requirements. and Pn is the nominal compressive strength of the composite column. except as modified in this Section. (2) The contribution of the reinforced-concrete-encased structural steel section to the strength of the column as provided in ACI 318.6.9. as specified for intermediate and special seismic systems in Sections 6.4a.2 through 11.6. shear connectors shall be provided to transfer the force Vu(1 - AsFy/Pn) between the structural steel section and the reinforced concrete.9.5. where As is the area of the structural steel section. PART II 56 Specification Chapter I.6. the dimension bw shall equal the width of the concrete cross-section minus the width of the structural shape measured perpendicular to the direction of shear. (b) If an external member is framed directly to the reinforced concrete to transfer a vertical reaction Vu. shall apply as required in the descriptions of the composite seismic systems in Sections 8 through 17. The nominal shear strength shall be multiplied by φv equal to 0.4c. (2) Composite columns that are designed to share the applied loads between the structural steel section and reinforced concrete shall have shear connectors that meet the following requirements: (a) If an external member is framed directly to the structural steel section to transfer a vertical reaction Vu. In ACI 318 Sections 11. (3) The seismic requirements for reinforced concrete columns as specified in the description of the composite seismic systems in Sections 8 through 17.5. Fy is the specified minimum yield strength of the structural steel section. Ordinary Seismic System Requirements The following requirements for reinforced-concrete-encased composite columns are applicable to all composite systems: (1) The nominal shear strength of the column shall be determined as the nominal shear strength of the structural shape plus the nominal shear strength that is provided by the tie reinforcement in the reinforced-concrete encasement.5. The nominal shear strength of the structural steel section shall be determined in accordance with LRFD Specification Section F2. 6.2.5 and 11. The nominal shear strength of the tie reinforcement shall be determined in accordance with ACI 318 Sections 11.6.4b and 6.5.75 to determine the design shear strength.
4b. (3) The maximum spacing of transverse ties shall be the least of the following: (a) one-half the least dimension of the section (b) 16 longitudinal bar diameters (c) 48 tie diameters Transverse ties shall be located vertically within one-half the tie spacing above the top of the footing or lowest beam or slab in any story and shall be spaced as provided herein within one-half the tie spacing below the lowest beam or slab framing into the column. The maximum spacing of other load carrying or restraining longitudinal reinforcement shall be one-half of the least side dimension of the composite member.1 and 12. Load-carrying reinforcement shall be provided at every corner of a rectangular cross-section. (c) The maximum spacing of shear connectors shall be 16 in. except that ties shall not be smaller than No. either at a transition to a pure reinforced concrete column or at the column base. Transverse bars shall have a diameter that is not less than one-fiftieth of greatest side dimension of the composite member. (5) Splices and end bearing details for reinforced-concrete-encased structural steel sections shall meet the requirements in the LRFD Specification and ACI 318 Section 7.2.8.4a: (1) The maximum spacing of transverse bars at the top and bottom shall be the least of the following: (a) one-half the least dimension of the section (b) 8 longitudinal bar diameters (c) 24 tie bar diameters 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . (406 mm) with attachment along the outside flange faces of the embedded shape.17. (4) All load-carrying reinforcement shall meet the detailing and splice requirements in ACI 318 Sections 7. Intermediate System Requirements Reinforced-concrete-encased composite columns in intermediate seismic systems shall meet the following requirements in addition to those in Section 6. Fy and Pn are as defined above. 5 bars. welded wire fabric of equivalent area is permitted as transverse reinforcement except when prohibited for intermediate and special systems. where As.57 PART II VuAsFy/Pn between the structural steel section and the reinforced concrete. If adverse behavioral effects due to the abrupt change in member stiffness and nominal tensile strength occur when reinforced-concrete encasement of a structural steel section is terminated.8. 3 bars and need not be larger than No. they shall be considered in the design. 6. Alternatively.
: (1) The required axial strength for reinforced-concrete-encased composite columns and splice details shall meet the requirements in Part I Section 8. 6. in. measured from each joint face and on both sides of any section where flexural yielding is expected to occur: (a) one-sixth the vertical clear height of the column (b) the maximum cross-sectional dimension (c) 18 in.4c. (mm) s = spacing of transverse reinforcement measured along the longitudinal axis of the structural member. (3) Welded wire fabric is not permitted as transverse reinforcement in intermediate seismic systems. and 6. (305 mm) These spacings shall be maintained over a vertical distance equal to the greatest of the following lengths. (2) Longitudinal load-carrying reinforcement shall meet the requirements in ACI 318 Section 21.y s c (6-2) Pn Fyh where hcc = cross-sectional dimension of the confined core measured center-to- center of the tie reinforcement. (3) Transverse reinforcement shall be hoop reinforcement as defined in ACI 318 Chapter 21 and shall meet the following requirements: (a) The minimum area of tie reinforcement Ash shall meet the following requirement: F A f ′ Ash = 0. ksi (MPa) 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .4.3. (457 mm) (2) Tie spacing over the remaining column length shall not exceed twice the spacing defined above. (mm) Fy = specified minimum yield strength of the structural steel core.2 (mm2) Pn = nominal axial compressive strength of the composite column calculated in accordance with the LRFD Specification. PART II 58 (d) 12 in.09 hcc s 1 .a. in. Special Seismic System Requirements Reinforced-concrete-encased columns for special seismic systems shall meet the following requirements in addition to those in Sections 6.4. in. ksi (MPa) As = cross-sectional area of the structural core.b. kips (N) f’c = specified compressive strength of concrete.4.
5.(6). such as walls or braced frames.0D+0.4c. the transverse reinforcement shall extend into the wall for at least the length required to develop full yielding in the reinforced-concrete-encased structural steel section and longitudinal reinforcement. (6) Reinforced-concrete-encased composite columns that are used in C-SMF shall meet the following requirements: (a) Transverse reinforcement shall meet the requirements in Section 6. (102 mm). legs of overlapping hoops. the maximum spacing of transverse reinforcement shall be the lesser of one-fourth the least member dimension and 4 in. and other confining reinforcement shall be spaced not more than 14 in. (5) Composite columns supporting reactions from discontinued stiff members.(3)(c) over the full length beneath the level at which the discontinuity occurs if the axial compression force exceeds 0. (b) The maximum spacing of transverse reinforcement along the length of the column shall be the lesser of 6 longitudinal load-carrying bar diameters and 6 in. Column bases shall be detailed to sustain inelastic flexural hinging.0D+0. cross ties.1 times Po. For this reinforcement. This requirement need not be satisfied if the nominal strength of the reinforced- concrete-encased structural steel section alone is greater than 1. 6.59 PART II Fyh = specified minimum yield strength of the ties.4c. (7) When the column terminates on a footing or mat foundation.4c.0D+0. (c) The minimum required shear strength of the column shall meet the requirements in ACI 318 Section 21. (305 mm).(3)(c) over the total element length. on center in the transverse direction. the transverse reinforcement as specified in this section shall extend into the footing or mat at least 12 in.4c.5L.5 shall be satisfied. (b) The strong-column/weak-beam design requirements in Section 9. ksi (MPa) Equation 6-2 need not be satisfied if the nominal strength of the reinforced-concrete- encased structural steel section alone is greater than 1.5L.4c(3)(c) at the top and bottom of the column over the region specified in Section 6. Transverse reinforcement shall extend into the discontinued member for at least the length required to develop full yielding in the reinforced-concrete-encased structural steel section and longitudinal reinforcement.4. (152 mm) (c) When specified in Sections 6.1. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .5L.(4).4c. This requirement need not be satisfied if the nominal strength of the reinforced-concrete- encased steel section alone is greater than 1. shall have transverse reinforcement as specified in Section 6. (4) Reinforced-concrete-encased composite columns in braced frames with axial compression forces that are larger than 0.2 times Po shall have transverse reinforcement as specified in Section 6.(5) or 6.4b. When the column terminates on a wall.
COMPOSITE CONNECTIONS 7. Column bases shall be designed to sustain inelastic flexural hinging.4. PART II 60 (8) Welded wire fabric is not permitted as transverse reinforcement for special seismic systems. Scope This Section is applicable to connections in buildings that utilize composite or dual steel and concrete systems wherein seismic force is transferred between structural steel and reinforced concrete components.1. ductility and toughness that is comparable to that exhibited by similar structural steel or reinforced concrete connections that meet the requirements in Part I and ACI 318. where b is as defined in LRFD Specification Table B5.5.1. 6. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . Methods for calculating the connection strength shall meet the requirements in this Section. 13 and 14. In the special seismic systems described in Sections 9. 7. and (2) meet the additional limitations in LRFD Specification Section I2. Such columns shall be designed to meet the requirements in LRFD Specification Chapter I.5.1. members and column splices for concrete-filled composite columns shall also meet the requirements in Part I Section 8. except as modified in this Section. (3) The minimum wall thickness of concrete-filled rectangular HSS shall equal b g b Fy / 2 E s (6-3) for the flat width b of each face. The design shear strength of the composite column shall be the design shear strength of the structural steel section alone. Concrete-filled Composite Columns This Section is applicable to columns that: (1) consist of concrete-filled steel rectangular or circular hollow structural sections (HSS) with a structural steel area that comprises at least 4 percent of the total composite-column cross-section. Concrete-filled composite columns used in C-SMF shall meet the following additional requirements: (1) The minimum required shear strength of the column shall meet the requirements in ACI 318 Section 21. Composite connections shall be demonstrated to have design strength. (2) The strong-column/weak-beam design requirements in Section 9.1.5 shall be met. respectively.
61 PART II 7. (4) The nominal shear strength of reinforced-concrete-encased steel panel-zones in beam- to-column connections shall be calculated as the sum of the nominal strengths of the structural steel and confined reinforced concrete shear elements as determined in Part I Section 9. respectively. Nominal Strength of Connections The nominal strength of connections in composite structural systems shall be determined on the basis of rational models that satisfy both equilibrium of internal forces and the strength limitation of component materials and elements based upon potential limit states. and 17. Structural steel elements that are encased in confined reinforced concrete are permitted to be considered to be braced against out-of-plane buckling. by shear friction with the necessary clamping force provided by reinforcement normal to the plane of shear transfer. except that the strength reduction (resistance) factors shall be as given in ACI 318.2. Any potential bond strength between structural steel and reinforced concrete shall be ignored for the purpose of the connection force transfer mechanism. the determination of the required connection strength shall account for any effects that result from the increase in the actual nominal strength of the connected member. force shall be transferred between structural steel and reinforced concrete through direct bearing of headed shear studs or suitable alternative devices. the models used for analysis of connections shall meet the following requirements: (1) When required.5. shall equal or exceed the required strengths. 13. (5) Reinforcement shall be provided to resist all tensile forces in reinforced concrete 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .3. Additionally. 14. connections that are required for the lateral stability of the building under seismic forces shall meet the requirements in Sections 8 through 17 based upon the specific system in which the connection is used. (2) The nominal bearing and shear-friction strengths shall meet the requirements in ACI 318 Chapters 10 and 11. 16. General Requirements Connections shall have adequate deformation capacity to resist the critical required strengths at the Design Story Drift. (3) The design strengths of structural steel components in composite connections.3 and ACI 318 Section 21. as determined in Part I and the LRFD Specification. Unless a higher strength is substantiated by cyclic testing. 7. or by a combination of these means. The strength reduction (resistance) factors for reinforced concrete shall be as given in ACI 318. by other mechanical means. the nominal bearing and shear-friction strengths shall be reduced by 25 percent for the composite seismic systems described in Sections 9. When the required strength is based upon nominal material strengths and nominal member dimensions. Unless the connection strength is determined by analysis and testing. Face Bearing Plates consisting of stiffeners between the flanges of steel beams are required when beams are embedded in reinforced concrete columns or walls.
the slab reinforcement shall be designed and anchored to carry the in-plane tensile forces at all critical sections in the slab.5. Limited yielding is permitted at other locations. as appropriate. Columns Structural steel columns shall meet the requirements in Part I Section 8 and the LRFD Specification. Connections shall meet the following additional requirements: (a) When the slab transfers horizontal diaphragm forces. C-PMRF shall meet the requirements of this section.4. braces and walls. beyond the point at which it is no longer required to resist the forces. The effect of PR moment connections on stability of individual columns and 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . Connection flexibility and composite beam action shall be accounted for in determining the dynamic characteristics. 11. Development lengths shall be determined in accordance with ACI 318 Chapter 12.2. Additionally. transverse hoop reinforcement shall be provided in the connection region to meet the requirements in ACI 318 Section 21. (b) For connections between structural steel or composite beams and reinforced concrete or reinforced-concrete-encased composite columns. columns. COMPOSITE PARTIALLY RESTRAINED (PR) MOMENT FRAMES (C-PRMF) 8. 12 and 15. except for the following modifications: (i) Structural steel sections framing into the connections are considered to provide confinement over a width equal to that of face bearing stiffener plates welded to the beams between the flanges. C-PRMF shall be designed so that under earthquake loading yielding occurs in the ductile components of the composite PR beam- to-column moment connections. 14.5. strength and drift of C-PRMF. All reinforcement shall be fully developed in tension or compression. PART II 62 components of the connections. 13. Scope This Section is applicable to frames that consist of structural steel columns and composite beams that are connected with partially restrained (PR) moment connections that meet the requirements in LRFD Specification Section A2. (c) The longitudinal bar sizes and layout in reinforced concrete and composite columns shall be detailed to minimize slippage of the bars through the beam-to- column connection due to high force transfer associated with the change in column moments over the height of the connection. 8. the concrete shall be confined with transverse reinforcement. 16 and 17 shall meet the requirements in ACI 318 Section 21.1. Additionally. (ii) Lap splices are permitted for perimeter ties when confinement of the splice is provided by Face Bearing Plates or other means that prevents spalling of the concrete cover in the systems described in Sections 10. development lengths for the systems described in Sections 9. such as the column base connection. including connections to collector beams. 8.
Partially Restrained (PR) Moment Connections The required strength for the beam-to-column PR moment connections shall be determined from the load combinations stipulated by the Applicable Building Code. but with limited inelastic deformations in the columns and/or connections. The nominal connection strength shall meet the requirements 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . 9.4 or 6. primarily in the beams. Beams Composite beams shall meet the requirements in Section 6. C-SMF shall be designed assuming that under the Design Earthquake significant inelastic deformations will occur.1.10.4. Reinforced concrete columns shall meet the requirements in ACI 318 Chapter 21.3. Columns Composite columns shall meet the requirements for special seismic systems in Sections 6.3. composite connections shall have a nominal strength that is at least equal to 50 percent of Mp. including consideration of the effects of connection flexibility and second-order moments. Neither structural steel nor composite trusses are permitted as flexural members to resist seismic loads in C-SMF unless it is demonstrated by testing and analysis that the particular system provides adequate ductility and energy dissipation capacity. where Mp is the nominal plastic flexural strength of the connected structural steel beam ignoring composite action. 9. In addition.03 radians that is substantiated by cyclic testing as described in Part I Section 9. 9. 9. C-SMF shall meet the requirements of this section.015 radians and a total rotation capacity of 0. COMPOSITE SPECIAL MOMENT FRAMES (C-SMF) 9.3. 8. For the purposes of analysis.4. Composite Beams Composite beams shall meet the requirements in LRFD Specification Chapter I. Connections shall meet the requirements in Section 7 and shall have an inelastic rotation capacity of 0. 8. Moment Connections The required strength of beam-to-column moment connections shall be determined from the shear and flexure associated with the nominal plastic flexural strength of the beams framing into the connection.5. the stiffness of beams shall be determined with an effective moment of inertia of the composite section.63 PART II the overall frame shall be considered in C-PRMF. excluding Section 21.2.2a. Scope This Section is applicable to moment-resisting frames that consist of either composite or reinforced concrete columns and either structural steel or composite beams.
2. the inelastic rotation capacity shall be demonstrated by testing or other substantiating data.5. PART II 64 in Section 7.3.10. C-IMF shall be designed assuming that under the Design Earthquake inelastic deformation will occur primarily in the beams but with moderate inelastic deformation in the columns and/or connections. In addition.1Po. 9.4 or 6. Pu.03 radians.4c(4). 10.6(a) shall be Pu < 0.6 with the following modifications: (1) The flexural strength of the composite column M*pc shall meet the requirements in LRFD Specification Chapter I with consideration of the applied axial load. Column-Beam Moment Ratio The minimum flexural strength and design of reinforced concrete columns shall meet the requirements in ACI 318 Section 21.5. For connections to reinforced concrete columns with a beam that is continuous through the column so that welded joints are not required in the flanges and the connection is not otherwise susceptible to premature fractures.4.4. Reinforced concrete columns shall meet the requirements in ACI 318 Section 21. the connections shall be capable of sustaining an inelastic beam rotation of 0. The minimum flexural strength and design of composite columns shall meet the requirements in Part I Section 9. 10.1 Scope This Section is applicable to moment resisting frames that consist of either composite or reinforced concrete columns and either structural steel or composite beams. (3) Composite columns exempted by the minimum flexural strength requirement in Part I Section 9. Moment Connections 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . 10.2. Beams Structural steel and composite beams shall meet the requirements in the LRFD Specification. COMPOSITE INTERMEDIATE MOMENT FRAMES (C-IMF) 10. C-IMF shall meet the requirements of this section. When the beam flanges are interrupted at the connection. the inelastic rotation capacity shall be demonstrated as specified in Part I Section 9 for connections in SMF. Columns Composite columns shall meet the requirements for intermediate seismic systems in Section 6. (2) The force limit for the exceptions in Part I Section 9. 10.6 shall have transverse reinforcement that meets the requirements in Section 6.
65 PART II The nominal connection strength shall meet the requirements in Section 7. columns and/or connections. C-OMF shall be designed assuming that under the Design Earthquake limited inelastic action will occur in the beams. 11. Beams Structural steel and composite beams shall meet the requirements in the LRFD Specification. Scope This Section is applicable to concentrically and eccentrically braced frame systems that consist of either composite or reinforced concrete columns. Reinforced concrete columns shall meet the requirements in ACI 318. 12. and structural steel or composite braces. COMPOSITE ORDINARY BRACED FRAMES (C-OBF) 12.4 or 6.2. columns. (c) The connections shall demonstrate an inelastic rotation capacity of at least 0. 11. C-OMF shall meet the requirements of this section.02 radians in cyclic tests. C-OBF shall be designed assuming that under the Design Earthquake limited inelastic action will occur in the beams. Moment Connections Connections shall be designed for the applied factored load combinations and their design strength shall meet the requirements in Section 7. Columns Composite columns shall meet the requirements for ordinary seismic systems in Section 6. COMPOSITE ORDINARY MOMENT FRAMES (C-OMF) 11. including the Amplified Seismic Load.1. (b) The connection design strength shall meet or exceed the required strength generated by load combinations stipulated by the Applicable Building Code.1. 11. Scope This Section is applicable to moment resisting frames that consist of either composite or reinforced concrete columns and structural steel or composite beams.5.3. excluding Chapters 21. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .4. structural steel or composite beams. The required strength of beam-to-column connections shall meet one of the following requirements: (a) The connection design strength shall meet or exceed the forces associated with plastic hinging of the beams adjacent to the connection. 11.
Beams Structural steel and composite beams shall meet the requirements in the LRFD 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . 13.4. PART II 66 braces. 12.1. 12. 12.5. and/or connections. Columns Reinforced-concrete-encased composite columns shall meet the requirements for ordinary seismic systems in Sections 6. Connections Connections shall be designed for the applied load combinations stipulated by the Applicable Building Code and their design strength shall meet the requirements in Section 7. Beams and braces shall be either structural steel or composite structural steel. 13. C-OBF shall meet the requirements of this section. Minor eccentricities are permitted if they are accounted for in the design.2. Columns Structural steel columns shall meet the requirements in Part I Section 8. Concrete-filled composite columns shall meet the requirements in Section 6. 12.3.2. C-CBF shall meet the requirements of this section.5.5. Reinforced concrete columns shall meet the requirements for structural truss elements in ACI 318 Chapter 21. Beams Structural steel and composite beams shall meet the requirements in the LRFD Specification. Scope This Section is applicable to braced systems that consist of concentrically connected members. COMPOSITE CONCENTRICALLY BRACED FRAMES (C-CBF) 13. C-CBF shall be designed so that under the loading of the Design Earthquake inelastic action will occur primarily through tension yielding and/or buckling of braces. Reinforced concrete columns shall meet the requirements in ACI 318 excluding Chapter 21. Braces Structural steel braces shall meet the requirements in the LRFD Specification.3.4. 13. Columns shall be either composite structural steel or reinforced concrete.2. Composite braces shall meet the requirements for composite columns in Section 12.4 or 6. Composite structural steel columns shall meet the requirements for special systems in Section 6.
4.a for composite columns) shall be provided above and below the Link connection.8.4c.1. 14. except as modified in this Section. columns. Composite columns shall meet the requirements for special seismic systems in Sections 6. It is permitted to encase the portion of the beam outside of the Link with reinforced concrete.6.4. 13. Braces shall be structural steel. Scope This Section is applicable to braced systems for which one end of each brace intersects a beam at an eccentricity from the intersection of the centerlines of the beam and column or intersects a beam at an eccentricity from the intersection of the centerlines of the beam and an adjacent brace.3. The diagonal braces.67 PART II Specification.4. 14. where a Link is adjacent to a reinforced concrete column or reinforced-concrete-encased column. 14.2. Braces Structural steel braces shall meet the requirements for SCBF in Part I Section 13.5. transverse reinforcement meeting the requirements in ACI 318 Section 21.4 or 6. Links Links shall be unencased structural steel and shall meet the requirement for EBF Links in Part I Section 15. Additionally.2. All columns shall meet the requirements in Part I Section 15. Beams containing the Link are permitted to act compositely with the floor slab using shear connectors along all or any portion of the beam if the composite action is considered when determining the nominal strength of the Link. C-EBF shall be designed so that inelastic deformations will occur only as shear yielding in the Links. Braces 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . and beam segments outside of the Link shall be designed to remain essentially elastic under the maximum forces that can be generated by the fully yielded and strain-hardened Link.4 (or Section 6. COMPOSITE ECCENTRICALLY BRACED FRAMES (C-EBF) 14. Links shall be structural steel as described in this Section. Columns shall be either composite or reinforced concrete. The design strength of members shall meet the requirements in the LRFD Specification.5. Composite braces shall meet the requirements for composite columns in Section 13. except as modified in this Section. Columns Reinforced concrete columns shall meet the requirements for structural truss elements in ACI 318 Chapter 21. C-EBF shall meet the requirements in Part I Section 15. 13. 14. Bracing Connections Bracing connections shall meet the requirements in Section 7 and Part I Section 13.
the structural steel sections shall meet the requirements in the LRFD Specification.4.4. if used. Headed shear studs or welded reinforcement anchors shall be provided to transfer vertical shear forces between the structural steel and reinforced concrete. PART II 68 Structural steel braces shall meet the requirements for EBF in Part I Section 15. such as reinforced concrete walls in structural steel frames with unencased or reinforced-concrete-encased structural steel sections that act as Boundary Members. Headed shear studs. if used. it shall be designed to meet the ordinary seismic system requirements in Section 6. C-ORCW shall meet the requirements of this section. shall meet the requirements in LRFD Specification Chapter I. Reinforced concrete walls shall meet the requirements in ACI 318 excluding Chapter 21. The wall shall meet the requirements in ACI 318 excluding Chapter 21. or as structural steel Coupling Beams that connect two adjacent reinforced concrete walls. 15.1. shall meet the requirements in AWS D1. ORDINARY REINFORCED CONCRETE SHEAR WALLS COMPOSITE WITH STRUCTURAL STEEL ELEMENTS (C-ORCW) 15.2. When the reinforced-concrete-encased structural steel Boundary Member qualifies as a composite column as defined in LRFD Specification Chapter I. connections shall meet the requirements in Section 7. Welded reinforcement anchors. Connections In addition to the requirements for EBF in Part I Section 15. Otherwise. 15. The required axial strength of the Boundary Member shall be determined assuming that the shear forces are carried by the reinforced concrete wall and the entire gravity and overturning forces are carried by the Boundary Members in conjunction with the shear wall. either as infill panels.5. 15. The reinforced concrete wall shall meet the requirements in ACI 318 excluding Chapter 21.3. Scope The requirements in this Section apply when reinforced concrete walls are composite with structural steel elements. When fully reinforced-concrete-encased structural steel sections function as Boundary Members in reinforced concrete infill panels. the analysis shall be based upon a transformed concrete section using elastic material properties. it shall be designed as a composite column to meet the requirements in ACI 318. Boundary Members When unencased structural steel sections function as Boundary Members in reinforced concrete infill panels. 14. Coupling Beams 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .
69 PART II
Structural steel Coupling Beams that are used between two adjacent reinforced concrete
walls shall meet the requirements in the LRFD Specification and this Section:
walls shall meet the requirements in the LRFD Specification and this Section:
Coupling Beams shall have an embedment length into the reinforced concrete wall that is
sufficient to develop the maximum possible combination of moment and shear that can be
generated by the nominal bending and shear strength of the Coupling Beam. The
embedment length shall be considered to begin inside the first layer of confining
reinforcement in the wall Boundary Member. Connection strength for the transfer of loads
between the Coupling Beam and the wall shall meet the requirements in Section 7.
sufficient to develop the maximum possible combination of moment and shear that can be
generated by the nominal bending and shear strength of the Coupling Beam. The
embedment length shall be considered to begin inside the first layer of confining
reinforcement in the wall Boundary Member. Connection strength for the transfer of loads
between the Coupling Beam and the wall shall meet the requirements in Section 7.
Vertical wall reinforcement with design axial strength equal to the nominal shear strength
of the Coupling Beam shall be placed over the embedment length of the beam with two-
thirds of the steel located over the first half of the embedment length. This wall
reinforcement shall extend a distance of at least one tension development length above and
below the flanges of the Coupling Beam. It is permitted to use vertical reinforcement
placed for other purposes, such as for vertical Boundary Members, as part of the required
vertical reinforcement.
of the Coupling Beam shall be placed over the embedment length of the beam with two-
thirds of the steel located over the first half of the embedment length. This wall
reinforcement shall extend a distance of at least one tension development length above and
below the flanges of the Coupling Beam. It is permitted to use vertical reinforcement
placed for other purposes, such as for vertical Boundary Members, as part of the required
vertical reinforcement.
16. SPECIAL REINFORCED CONCRETE SHEAR WALLS COMPOSITE WITH
STRUCTURAL STEEL ELEMENTS (C-SRCW)
STRUCTURAL STEEL ELEMENTS (C-SRCW)
16.1. Scope
C-SRCW systems shall meet the requirements in Section 15 for C-ORCW and the shear-
wall requirement in ACI 318 including Chapter 21, except as modified in this Section.
wall requirement in ACI 318 including Chapter 21, except as modified in this Section.
16.2. Boundary Members
In addition to the requirements in Section 15.2a, unencased structural steel columns shall
meet the requirements in Part I Sections 5, 6 and 8.
meet the requirements in Part I Sections 5, 6 and 8.
Walls with reinforced-concrete-encased structural steel Boundary Members shall meet the
requirements in Section 15.2 as wells as the requirements in this Section. The wall shall
meet the requirements in ACI 318 including Chapter 21. Reinforced-concrete-encased
structural steel Boundary Members that qualify as composite columns in LRFD
Specification Chapter I shall meet the special seismic system requirements in Section 6.4.
Otherwise, such members shall be designed as composite compression members to meet
the requirements in ACI 318 including the special seismic requirements for Boundary
Members in Chapter 21. Transverse reinforcement for confinement of the composite
Boundary Member shall extend a distance of 2h into the wall where h is the overall depth
of the Boundary Member in the plane of the wall.
requirements in Section 15.2 as wells as the requirements in this Section. The wall shall
meet the requirements in ACI 318 including Chapter 21. Reinforced-concrete-encased
structural steel Boundary Members that qualify as composite columns in LRFD
Specification Chapter I shall meet the special seismic system requirements in Section 6.4.
Otherwise, such members shall be designed as composite compression members to meet
the requirements in ACI 318 including the special seismic requirements for Boundary
Members in Chapter 21. Transverse reinforcement for confinement of the composite
Boundary Member shall extend a distance of 2h into the wall where h is the overall depth
of the Boundary Member in the plane of the wall.
Headed shear studs or welded reinforcing bar anchors shall be provided as specified in
Section 15.2c. For connection to unencased structural steel sections, the nominal strength
of welded reinforcing bar anchors shall be reduced by 25 percent from their Static Yield
Strength.
Section 15.2c. For connection to unencased structural steel sections, the nominal strength
of welded reinforcing bar anchors shall be reduced by 25 percent from their Static Yield
Strength.
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AMERICAN INSTITUTE OF STEEL CONSTRUCTION
AMERICAN INSTITUTE OF STEEL CONSTRUCTION
PART II 70
16.3. Coupling Beams
In addition to the requirements in Section 15.3a, structural steel Coupling Beams shall
meet the requirements in Part I Sections 15.2 and 15.3. When required in Part I Section
15.3, the coupling rotation shall be assumed as 0.08 radians unless a smaller value is
justified by rational analysis of the inelastic deformations that are expected under the
Design Earthquake. Face Bearing Plates shall be provided on both sides of the Coupling
Beams at the face of the reinforced concrete wall. These stiffeners shall meet the detailing
requirements in Part I Section 15.3.
meet the requirements in Part I Sections 15.2 and 15.3. When required in Part I Section
15.3, the coupling rotation shall be assumed as 0.08 radians unless a smaller value is
justified by rational analysis of the inelastic deformations that are expected under the
Design Earthquake. Face Bearing Plates shall be provided on both sides of the Coupling
Beams at the face of the reinforced concrete wall. These stiffeners shall meet the detailing
requirements in Part I Section 15.3.
Vertical wall reinforcement as specified in Section 15.3 shall be confined by transverse
reinforcement that meets the requirements for Boundary Members in ACI 318 Section 21.
7.2.
reinforcement that meets the requirements for Boundary Members in ACI 318 Section 21.
7.2.
17. COMPOSITE STEEL PLATE SHEAR WALLS (C-SPW)
17.1. Scope
This Section is applicable to structural walls consisting of steel plates with reinforced
concrete encasement on one or both sides of the plate and structural steel or composite
Boundary Members. C-SPW shall meet the requirements of this section.
concrete encasement on one or both sides of the plate and structural steel or composite
Boundary Members. C-SPW shall meet the requirements of this section.
17.2. Wall Elements
17.2a. Nominal Shear Strength
The nominal shear strength of C-SPW with a stiffened plate conforming to Section 17.2b
shall be determined as:
shall be determined as:
Vns = 0.6AspFy (17-1)
where
Vns = nominal shear strength of the steel plate, kips (N)
Asp = horizontal area of stiffened steel plate, in2 (mm2)
Fy = specified minimum yield strength of the plate, ksi (MPa)
Asp = horizontal area of stiffened steel plate, in2 (mm2)
Fy = specified minimum yield strength of the plate, ksi (MPa)
The nominal shear strength of C-SPW with a plate that does not meet the stiffening
requirements in Section 17.2b shall be based upon the strength of the plate, excluding the
strength of the reinforced concrete, and meet the requirements in the LRFD Specification,
including the effects of buckling of the plate.
requirements in Section 17.2b shall be based upon the strength of the plate, excluding the
strength of the reinforced concrete, and meet the requirements in the LRFD Specification,
including the effects of buckling of the plate.
17.2b. Detailing Requirements
The steel plate shall be adequately stiffened by encasement or attachment to the reinforced
concrete if it can be demonstrated with an elastic plate buckling analysis that the composite
wall can resist a nominal shear force equal to Vns. The concrete thickness shall be a
2002 Seismic Provisions
AMERICAN INSTITUTE OF STEEL CONSTRUCTION
concrete if it can be demonstrated with an elastic plate buckling analysis that the composite
wall can resist a nominal shear force equal to Vns. The concrete thickness shall be a
2002 Seismic Provisions
AMERICAN INSTITUTE OF STEEL CONSTRUCTION
71 PART II
minimum of 4 in. (102 mm) on each side when concrete is provided on both sides of the
steel plate and 8 in. (203 mm) when concrete is provided on one side of the steel plate.
Headed shear stud connectors or other mechanical connectors shall be provided to prevent
local buckling and separation of the plate and reinforced concrete. Horizontal and vertical
reinforcement shall be provided in the concrete encasement to meet the detailing
requirements in ACI 318 Section 14.3. The reinforcement ratio in both directions shall not
be less than 0.0025; the maximum spacing between bars shall not exceed 18 in. (457 mm).
steel plate and 8 in. (203 mm) when concrete is provided on one side of the steel plate.
Headed shear stud connectors or other mechanical connectors shall be provided to prevent
local buckling and separation of the plate and reinforced concrete. Horizontal and vertical
reinforcement shall be provided in the concrete encasement to meet the detailing
requirements in ACI 318 Section 14.3. The reinforcement ratio in both directions shall not
be less than 0.0025; the maximum spacing between bars shall not exceed 18 in. (457 mm).
The steel plate shall be continuously connected on all edges to structural steel framing and
Boundary Members with welds and/or slip-critical high-strength bolts to develop the
nominal shear strength of the plate. The design strength of welded and bolted connectors
shall meet the additional requirements in Part I Section 7.
Boundary Members with welds and/or slip-critical high-strength bolts to develop the
nominal shear strength of the plate. The design strength of welded and bolted connectors
shall meet the additional requirements in Part I Section 7.
17.3. Boundary Members
Structural steel and composite Boundary Members shall be designed to meet the
requirements in Section 16.2.
requirements in Section 16.2.
Boundary Members shall be provided around openings as required by analysis.
2002 Seismic Provisions
AMERICAN INSTITUTE OF STEEL CONSTRUCTION
AMERICAN INSTITUTE OF STEEL CONSTRUCTION
PART III 72 Part III Allowable Stress Design (ASD) Alternative As an alternative to the Load and Resistance Factor Design (LRFD) provisions for structural steel design in Part I. These Provisions shall apply to buildings that are classified in the Applicable Building Code as Seismic Design Category D (or equivalent) and higher or when required by the Engineer of Record. 1. “Type 1”. REFERENCED SPECIFICATIONS. SCOPE Substitute the following for PART I Section 1 in its entirety: These Provisions are intended for the design and construction of structural steel members and connections in the Seismic Force Resisting Systems in buildings for which the design forces resulting from earthquake motions have been determined on the basis of various levels of energy dissipation in the inelastic range of response. respectively. June 23. 1989 including Supplement No. December 17. 1. All members and connections in the Seismic Force Resisting System shall be proportioned as required in the ASD Specification to resist the applicable load combinations and shall meet the requirements in these Provisions. When using this Part. “FR” and “PR” in Part I shall be taken as “ASD Specification”. June 1. AND STANDARDS Substitute the following for the first two paragraphs of Part I Section 2: The documents referenced in these Provisions shall include those listed in ASD Specification Section A6 with the following additions and modifications: American Institute of Steel Construction Specification for Structural Steel Buildings—Allowable Stress Design and Plastic Design. and “Type 3”. hereinafter referred to as the ASD Specification. All requirements of Part I shall be met except as modified or supplemented in this Part. 2001 Substitute the following for the last paragraph of Part I Section 2: Research Council on Structural Connections Specification for Structural Joints Using ASTM A325 or A490 Bolts. 2. Part III includes the Part I Glossary and Appendix S. the use of the Allowable Stress Design (ASD) provisions in this Part is permitted. Appendix B 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . the terms “LRFD Specification”. 1. 2000. CODES. These Provisions shall be applied in conjunction with the AISC Specification for Structural Steel Buildings—Allowable Stress Design and Plastic Design including Supplement No.
and K. G. J. Design Strength The design strength of structural steel members and connections subjected to seismic forces in combination with other prescribed loads shall be determined by converting allowable stresses into nominal strengths and multiplying such nominal strengths by the resistance factors given in Table III-4-1. in. (mm) rb = the corresponding radius of gyration.73 PART III 4. in. The 1/3 allowable stress increase shall not be applied in conjunction with this factor. LOADS.7 times the allowable stresses in Section D. LOAD COMBINATIONS.” Amend the first paragraph of ASD Specification Section N1 by deleting “or earthquake” and adding: “The nominal strength of members and connections shall be determined by the requirements contained herein. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .” In ASD Specification Section H1 the definition of Fe′ shall read as follows: π 2 Es Fe′ = (4-1) ( Klb / rb ) 2 where: lb = the actual length in the plane of bending. H. E.2 in its entirety: 4.2 Nominal Strength The nominal strengths of members and connections shall be determined as follows: Replace ASD Specification Section A5. all pertinent requirements of Chapters A through M shall govern.2 with the following: “The nominal strength of structural steel members and connections for resisting seismic forces acting alone or in combination with dead and live loads shall be determined by multiplying 1. Except as modified in these provisions. AND NOMINAL STRENGTHS Substitute the following for Part I Section 4.3. (mm) K = the effective length factor in the plane of bending 4. F.
90 Weld metal 0.90 Shear on effective area Base metal 0.90 Tension normal to effective area Base metal 0.0 oversized holes.85 Slip resistance for bolts in long-slotted holes with the slot parallel to the direction of the slot Connecting elements 0.80 Shear parallel to axis of weld Weld metal 0.90 Complete-joint-penetration groove welds Tension or compression normal to effective area Base metal 0.90 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . and short-slotted holes Slip resistance for bolts in long-slotted holes 1.90 Weld metal 0. 1.0 with the slot perpendicular to the direction of the slot 0. PART III 74 TABLE III-4-1 Resistance Factors for ASD Limit State Resistance Factor Tension Yielding 0.90 Weld metal 0.75 Torsion Yielding 0.90 Rupture 0. shear rupture.75 and shear Slip resistance for bolts in standard holes.90 Rupture 0.90 Weld metal 0. combined tension 0.75 Compression buckling 0.85 Flexure Yielding 0.90 Buckling 0.75 Shear Yielding 0.90 Rupture 0.75 Fillet welds Shear on effective area Weld metal 0.75 Plug or slot welds Shear parallel to faying surface (on effective area) Weld metal 0.75 Bolts Tension rupture.80 Partial-joint-penetration groove welds Compression normal to effective area Base metal 0.
2 fourth paragraph in its entirety: The design resistance to shear and combined tension and shear of bolted joints shall be determined in accordance with the ASD Specification Sections J3. The design shear strength φvRv of the panel zone shall be determined using φv = 1.7. panel-zone web shear 0. CONNECTIONS. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . shear rupture. Bolted Joints Substitute the following for Part I Section 7. tension rupture. 3bcf t cf2 Rv = 0.75 Web crippling.75Py.75Py.85 Sidesway web buckling 7. the required shear strength Ru of the panel zone shall be determined from the summation of the moments at the column faces as determined by projecting the expected moments at the plastic hinge points to the column faces. compression buckling of web 1. As a minimum. AND FASTENERS 7.3a in its entirety: The required thickness of the panel zone shall be determined in accordance with the method used in proportioning the panel zone of the tested connection.60 Contact bearing Flanges and webs with concentrated forces 0.3 Panel Zone of Beam-to-Column Connections (beam web parallel to column web) Substitute the following for Part I Section 9. JOINTS. block shear rupture Bearing on steel 0. shear yielding 0.75 PART III Tension yielding. except that the allowable bearing stress at bolt holes Fp shall not be taken greater than 1.2.75 Bearing strength at bolt holes.6 Fy d c t p 1 + (9-1) d b d c t p When Pu > 0. SPECIAL MOMENT FRAMES 9.0 Local web yielding 0. When Pu ≤ 0.0.2Fu.75 Bearing on concrete 0.5 and J3. 9.90 Local flange bending.
13.4 Nominal Strength of Non-special Segment Members Substitute the following for the first sentence in Part I Section 12. in. (mm) Fy = specified minimum yield strength of the panel-zone steel.6 Lateral Bracing Substitute the following for the first sentence in Part I Section 12.4a(2) in its entirety: (2) A beam that is intersected by braces shall be designed to support the effects of all tributary dead and live loads assuming that the bracing is not present.6 Fy d c t p 1 + 19. along the entire length of the truss. SPECIAL CONCENTRICALLY BRACED FRAMES (SCBF) Substitute the following for Part I Section 13. in. PART III 76 3bcf t cf2 .7b(1) in its entirety: The required column strength shall be determined from the ASD load combinations stipulated in the Applicable Building Code. − . (9-1a) d b d c t p Py where tp = total thickness of panel-zone including doubler plate(s). except that E shall be taken as the lesser of: (a) The Amplified Seismic Load (b) 125 percent of the frame design strength based upon either the beam design flexural strength or panel-zone design shear strength 12. (mm) tcf = thickness of the column flange. except those in the special segment defined in Section 12.6: The top and bottom chords of the trusses shall be laterally braced at the ends of the special segment. SPECIAL TRUSS MOMENT FRAMES 12. (mm) dc = overall column depth. in. and at intervals not to exceed Lc according to ASD Specification Section F1.2. in. (mm) bcf = width of the column flange.4: Members and connections of STMF. (mm) db = overall beam depth. ksi (MPa) 9. in.7 Beam-to-Column Connection Restraint Substitute the following for Part I Section 9. Pu 12 Rv = 0. shall have a design strength to resist ASD load combinations as stipulated by the Applicable Building Code replacing the earthquake load term E with the lateral loads necessary to develop the expected vertical nominal shear strength in the special segment Vne given as: [balance to remain unchanged] 12. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION .
This load effect shall be calculated using a minimum of Py for the brace in tension and a maximum of 0. ORDINARY CONCENTRICALLY BRACED FRAMES (OCBF) Substitute the following for Part I Section 14. Qb is the maximum unbalanced vertical load effect applied to the beam by the braces.2 in its entirety: 14.77 PART III Substitute the following for Part I Section 13. 14. Braces with Kl/r greater than 4. other than brace connections.2. 2002 Seismic Provisions AMERICAN INSTITUTE OF STEEL CONSTRUCTION . determined as Ry Fy Ag. The design strength of brace connections shall equal or exceed the expected tensile strength of the brace.23 E s / Fy shall not be used in V or inverted-V configurations. except that a load Qb shall be substituted for the term E. Strength The required strength of the members and connections.3 times φcPn for the brace in compression. in OCBFs shall be determined using the ASD load combinations stipulated by the Applicable Building Code except E shall be taken as the Amplified Seismic Load.4a(3) in its entirety: (3) A beam that is intersected by braces shall be designed to resist the effects of ASD load combinations as stipulated by the Applicable Building Code.
Book Description:
Title: - Aisc Seismic Design Manual Rn39261 Pdf Enligne 2019
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Title: - Aisc Seismic Design Manual Rn39261 Pdf Enligne 2019
File Type: PDF EPUB MOBI.
MD5 Hash Code: 5b3384b854ad2b85325d4ba54d4256e9
ASIN/ISBN:
Recent Member Activity